Exhibit 99.1

STERIS CORPORATION

NEWS ANNOUNCEMENT

FOR IMMEDIATE RELEASE

STERIS CORPORATION ANNOUNCES FISCAL 2012 FOURTH QUARTER

AND FULL YEAR RESULTS

• Board of Directors Approves Quarterly Dividend Payment

• Company Provides Fiscal 2013 Outlook

Mentor, Ohio (May 8, 2012)—STERIS Corporation (NYSE: STE) today announced financial results for its fiscal 2012 fourth quarter ended March 31, 2012. Included in the financial results is a $17.4 million pre-tax adjustment, based on actual experience to date, of the SYSTEM 1 Rebate Program liability, which was originally recorded in the first quarter of fiscal 2011. As reported, fiscal 2012 fourth quarter revenue was $390.2 million compared with $377.8 million in the fourth quarter of fiscal 2011. Operating income for the fourth quarter was $74.0 million compared with $57.5 million in the fourth quarter of fiscal 2011. Net income was $44.2 million, or $0.76 per diluted share, compared with net income of $39.0 million, or $0.65 per diluted share in the fourth quarter of fiscal 2011.

Of the $17.4 million pre-tax adjustment, $15.3 million is attributable to the Customer Rebate portion of the Program and was recorded as an increase to revenue, and $2.1 million is attributable to the disposal costs of SYSTEM 1 units to be returned and was recorded as a reduction in cost of revenue. Adjusted financials disclosed in this press release exclude the $17.4 million Rebate Program adjustment, restructuring expenses from the Company’s ongoing efficiency efforts, an inventory write-down related to certain SYSTEM 1E components and the impact of the original SYSTEM 1 Rebate Program and class action settlement, as appropriate. Please refer to the attached schedules for additional information, including reconciliations from these “non-GAAP financial measures” to as reported results.

Adjusted Financial Results

Adjusted revenue for the fourth quarter of fiscal 2012 was $374.9 million, a decline of 1%. Operating income for the fourth quarter of fiscal 2012 was $58.7 million or 15.7% of revenue, compared with operating income for the fourth quarter of fiscal 2011 of $58.2 million or 15.4% of revenue. Operating income improved slightly year-over-year as a result of lower operating expenses. Net income for the fourth quarter of fiscal 2012 was $34.3 million, or $0.59 per diluted share compared with net income for the fourth quarter of fiscal 2011 of $36.4 million, or $0.61 per diluted share.

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“We are pleased to demonstrate solid top-line growth in every business in fiscal 2012, with the exception of our Healthcare consumables franchise, which continues to be impacted by the decline in S20 sterilant,” said Walt Rosebrough, President and Chief Executive Officer of STERIS. “Our bottom-line performance was hindered by several factors, but ended the year in-line with our expectations. We anticipate that fiscal 2013 will be a turning point for the Company, as we complete the SYSTEM 1 transition and establish a new foundation from which we intend to grow revenue and earnings in the future.”

Segment Results

As reported, Healthcare revenue in the quarter was $287.6 million compared with $274.1 million in the fourth quarter of fiscal 2011. Adjusted revenue was $272.3 million in the fourth quarter of fiscal 2012, down less than 1% from the prior year. Contributing to the quarter, service revenue grew 4%, and capital equipment revenue grew 1%, while consumable revenue declined 9% as the Company experienced a continued drop-off in S20 Sterilant volumes. Within capital equipment, excluding SYSTEM 1E unit sales, capital equipment grew 7%, with strong growth in both infection prevention and surgical products. As reported, operating income was $53.5 million compared with $40.8 million in last year’s fourth quarter. Adjusted segment operating income was $38.2 million in the fourth quarter of fiscal 2012 compared with $41.3 million in the fourth quarter of fiscal 2011. The decline in adjusted operating income year-over-year was primarily due to lower S20 sterilant volumes and fewer SYSTEM 1E unit shipments.

Life Sciences fourth quarter revenue declined 8% to $59.0 million compared with $64.1 million in the fourth quarter of fiscal 2011. Consumable revenue growth of 10% was more than offset by a 24% decline in capital equipment revenue and a 2% decrease in service revenue. Life Sciences operating income was $10.8 million compared with $10.0 million in the prior year fourth quarter. The increase in operating income was driven by lower operating expenses.

Fiscal 2012 fourth quarter revenue for Isomedix Services was $42.6 million compared with $38.5 million in the same period last year, an increase of 11%. Revenue benefited from increased volumes from core medical device Customers and market share gains. Operating income was $11.7 million in the quarter compared with $9.0 million in the fourth quarter of last year. The increase in operating income is primarily attributable to the improved volume.

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Full Year Results

As reported, fiscal 2012 revenue was $1.41 billion, compared with $1.21 billion in fiscal 2011. Adjusted revenue for fiscal 2012 increased 6% to $1.39 billion compared with $1.31 billion in fiscal 2011, with mid-single digit growth occurring in all three business segments.

As reported, fiscal 2012 operating income was $222.3 million compared with $85.2 million in fiscal 2011. Adjusted operating income was $208.4 million in fiscal 2012 compared with $216.4 million in fiscal 2011.

As reported, fiscal 2012 net income was $136.1 million, or $2.31 per diluted share, compared with net income of $51.3 million, or $0.85 per diluted share in fiscal 2011. Adjusted net income for fiscal 2012 was $127.2 million or $2.16 per diluted share compared with $131.7 million or $2.19 per diluted share in fiscal 2011.

Cash Flow

Net cash provided by operations for fiscal 2012 was $149.4 million, compared with $117.7 million last year. Free cash flow (see note 1) for fiscal 2012 was $82.7 million, compared with $41.6 million in the prior year. The increase in free cash flow was driven by a decline in working capital requirements.

During fiscal 2012, the Company repurchased approximately 1.9 million shares of its common stock at an average price of $30.21 per share for a total amount of $56.0 million. Approximately $118 million remains available for additional purchases under the current share repurchase authorization.

Dividend Announcement

The Company announced today that STERIS’s Board of Directors has authorized a quarterly dividend of $0.17 per common share. The dividend is payable June 26, 2012 to shareholders of record at the close of business on June 5, 2012.

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Outlook

Based upon current trends, the Company expects revenue to be flat in fiscal 2013 when compared with adjusted revenue in fiscal 2012 and earnings per diluted share to be in the range of $2.00 to $2.20 for the full fiscal year. This outlook reflects certain key assumptions, some of which are listed below:

For the full fiscal year 2013, free cash flow (see note 1) is anticipated to be approximately $120 million excluding the SYSTEM 1 Rebate Program and class action settlement, or $80 million as reported including those items. Capital expenditures are anticipated to be approximately $85 million, as the Company is investing in several major projects within its facilities that are designed to improve quality, reduce cost and add value to our current product offering.

Conference Call

In conjunction with this release, STERIS Corporation management will host a conference call today at 10:00 a.m. Eastern time. The conference call can be heard live over the Internet at www.steris-ir.com or via phone by dialing 1-800-369-8428 in the United States and Canada, and 1-773-799-3378 internationally, then referencing the password “STERIS”.

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For those unable to listen to the conference call live, a replay will be available beginning at 12:00 p.m. Eastern time on May 8, 2012, either over the Internet at www.steris-ir.com or via phone by calling 1-866-498-5468 in the United States and Canada, and 1-203-369-1798 internationally.

Annual Meeting of Shareholders

The Company will hold its annual meeting of shareholders on July 26, 2012. Further information regarding the time and location will be provided in the Company’s annual report and proxy materials.

About STERIS

The mission of STERIS Corporation is to provide a healthier today and safer tomorrow through knowledgeable people and innovative infection prevention, decontamination and health science technologies, products and services. The Company has approximately 5,000 dedicated employees around the world working together to supply a broad array of solutions by offering a combination of equipment, consumables and services to healthcare, pharmaceutical, industrial and government Customers. The Company is listed on the New York Stock Exchange under the symbol STE. For more information, visit www.steris.com.

(1) Free cash flow is a non-GAAP number used by the Company as a measure to gauge its ability to fund future debt principal repayments, growth outside of core operations, repurchase common shares, and pay cash dividends. Free cash flow is defined as cash flows from operating activities less purchases of property, plant, equipment and intangibles, net, plus proceeds from the sale of property, plant, equipment and intangibles. STERIS’s calculation of free cash flow may vary from other companies.

# # #

This press release and the referenced conference call may contain statements concerning certain trends, expectations, forecasts, estimates, or other forward-looking information affecting or relating to the Company or its industry, products or activities that are intended to qualify for the protections afforded “forward-looking statements” under the Private Securities Litigation Reform Act of 1995 and other laws and regulations. Forward-looking statements speak only as to the date of this report, and may be identified by the use of forward-looking terms such as “may,” “will,” “expects,” “believes,” “anticipates,” “plans,” “estimates,” “projects,” “targets,” “forecasts,” “outlook,” “impact,” “potential,” “confidence,” “improve,” “optimistic,” “deliver,” “comfortable,” “trend”, and “seeks,” or the negative of such terms or other variations on such terms or comparable terminology. Many important factors could cause actual results to differ materially from those in the forward-looking statements including, without limitation, disruption of production or supplies, changes in market conditions, political events, pending or future claims or litigation, competitive factors, technology advances, actions of regulatory agencies, and changes in laws, government regulations, labeling or product approvals or the application or interpretation thereof. Other risk factors are described herein and in the Company’s Form 10-K and other securities filings. Many of these important factors are outside STERIS’s control. No assurances can be provided as to any result or the timing of any outcome regarding matters described in this release, the referenced conference call or otherwise with respect to any regulatory action, administrative proceedings, government investigations, litigation, warning letters, consent decree, rebate program, transition, cost reductions, business strategies, earnings or revenue trends or future financial results (including without limitation the settlement of the SYSTEM 1 class action litigation and the regulatory matters related to SYSTEM 1E or its

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accessories). References to products, the consent decree, the transition or rebate program, or the class action settlement, are summaries only and should not be considered the specific terms of the decree, settlement, program or product clearance or literature. Unless legally required, the Company does not undertake to update or revise any forward-looking statements even if events make clear that any projected results, express or implied, will not be realized. Other potential risks and uncertainties that could cause actual results to differ materially from those in the forward-looking statements include, without limitation, (a) the potential for increased pressure on pricing or costs that leads to erosion of profit margins, (b) the possibility that market demand will not develop for new technologies, products or applications or the Company’s rebate program, transition plan or other business initiatives will take longer, cost more or produce lower benefits than anticipated, (c) the possibility that application of or compliance with laws, court rulings, certifications, regulations, regulatory actions, including without limitation those relating to FDA warning letters, government investigations, the December 3, 2009 or February 22, 2010 FDA notices, the April 20, 2010 consent decree and related transition plan and rebate program, the SYSTEM 1E device, the outcome of any pending FDA requests, inspections or submissions, or other requirements or standards may delay, limit or prevent new product introductions, affect the production and marketing of existing products or services or otherwise affect Company performance, results, prospects or value, (d) the potential of international unrest, economic downturn or effects of fluctuations in currencies, tax assessments or anticipated rates, raw material costs or availability, benefit or retirement plan costs, or other regulatory compliance costs, (e) the possibility of reduced demand, or reductions in the rate of growth in demand, for the Company’s products and services, (f) the possibility that anticipated growth, cost savings, rebate assumptions, new product acceptance, performance or approvals, including without limitation SYSTEM 1E and accessories thereto, or other results may not be achieved, or that transition, labor, competition, timing, execution, regulatory, governmental, or other issues or risks associated with our business, industry or initiatives including, without limitation, the consent decree, rebate program, and the transition from the SYSTEM 1 processing system or those matters described in our Form 10-K for the year ended March 31, 2011 and other securities filings, may adversely impact company performance, results, prospects or value, (g) the effect of the contraction in credit availability, as well as the ability of our Customers and suppliers to adequately access the credit markets when needed, and (h) those risks described in our securities filings including our Annual Report on Form 10-K for the year ended March 31, 2011, and other securities filings.

Contact: Julie Winter, Director, Investor Relations at 440-392-7245.

STERIS Corporation

Consolidated Condensed Statements of Operations

(In thousands, except per share data)

STERIS Corporation

Consolidated Condensed Balance Sheets

(In thousands)

STERIS Corporation

Segment Data

(In thousands)

STERIS Corporation

Consolidated Condensed Statements of Cash Flows

(In thousands)

The following table presents a financial measure which is considered to be "non-GAAP financial measures" under Securities Exchange Commission rules. Free cash flow is defined by the Company as cash flows from operating activities less purchases of property, plant, equipment and intangibles, net (capital expenditures) plus proceeds from the sale of property, plant, equipment and intangibles. The Company uses free cash flow as a measure to gauge its ability to fund future principal debt repayments, growth outside of core operations, repurchase common shares, and pay cash dividends. STERIS's calculation of free cash flow may vary from other companies.

STERIS Corporation

Unaudited Supplemental Financial Data

Fourth Quarter Fiscal 2012

As of March 31, 2012

This supplemental data is consistent with publicly disclosed information provided in quarterly conference calls, earnings releases and SEC filings, and is subject to all definitions, precautions and limitations contained in those disclosures. Please see the Company's most recent 10-K for definitions (and reconciliation where appropriate) of adjusted measures, backlog, free cash flow and net debt.

STERIS Corporation

Non-GAAP Financial Measures

(In thousands, except per share data)

The Company has referred to certain adjusted financial measures regarding the results of operations excluding certain items to provide meaningful comparative analysis between the periods. These financial measures are considered to be “non-GAAP financial measures” under Securities Exchange Commission rules. Reconciliation of each financial measure to its nearest GAAP financial measure is provided in the table below.