Exhibit 99.1

GI Dynamics, Inc. – ASX Announcement

Appendix 4E Preliminary Final Report

Year ended 31 December 2015

LEXINGTON, Massachusetts, United States and SYDNEY, Australia – 26 February 2016 – GI Dynamics, Inc. (ASX: GID) (GI Dynamics or the Company), a medical device company developing innovative treatments for type 2 diabetes and obesity, today announced its preliminary financial results for the year ended 31 December 2015 (“Results”). The Appendix 4E, which has been prepared in U.S. dollars and in accordance with U.S. GAAP, is attached; the Results disclosed in the Appendix 4E are unaudited. The financial results are currently being audited by the Company’s auditors, Ernst & Young LLP, with final audited results to be filed as part of the Annual Report on Form 10-K with the U.S. Securities and Exchange Commission and the Australian Securities Exchange on or before 31 March 2016.

Summary of the Results

Please refer to the attached Appendix 4E, including the unaudited consolidated financial statements, for additional explanation and details.

Robert Solomon

Vice President, Finance & Company Secretary

www.gidynamics.com

About GI Dynamics

GI Dynamics, Inc. (ASX: GID) is the developer of EndoBarrier^®, the first endoscopically-delivered device therapy approved for the treatment of obese type 2 diabetes with BMI ³ 30 kg/m², or obese patients with BMI ³ 30 kg/m² with ³ 1 comorbidities, or obese patients with BMI >35 kg/m². The liner is indicated for a maximum implant duration of 12 months. EndoBarrier is approved and commercially available in multiple countries outside the U.S. EndoBarrier is not approved for sale in the U.S. and is limited by federal law to investigational use only in the United States. Founded in 2003, GI Dynamics is headquartered in Lexington, Massachusetts. For more information, please visit www.gidynamics.com.

Forward-Looking Statements

This announcement contains forward-looking statements concerning: our development and commercialization plans; our potential revenues and revenue growth, costs, excess inventory, profitability and financial performance; our ability to obtain reimbursement for our products; our clinical trials, and associated regulatory submissions and approvals; the number and location of commercial centres offering the EndoBarrier; and our intellectual property position. These forward-looking statements are based on the current estimates and expectations of future events by the management of GI Dynamics, Inc. as of the date of this announcement and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those indicated in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: risks associated with the consequences of terminating the ENDO Trial and the possibility that future clinical trials will not be successful or confirm earlier results; risks associated with obtaining funding from third parties; risks relating to the timing and costs of clinical trials, the timing of regulatory submissions, the timing, receipt and maintenance of regulatory approvals, the timing and amount of other expenses, and the timing and extent of third-party reimbursement; risks associated with commercial product sales, including product performance; competition; risks related to market acceptance of products; intellectual property risks; risks related to excess inventory; risks related to assumptions regarding the size of the available market, benefits of our products, product pricing, timing of product launches, future financial results and other factors including those described in our filings with the U.S. Securities and Exchange Commission. Given these uncertainties, you should not place undue reliance on these forward-looking statements. We do not assume any obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, unless required by law.

Investor Enquiries:

United States:

Robert Solomon, Vice President, Finance and Company Secretary

+1 (781) 357-3246

Australia:

David Allen or John Granger

Hawkesbury Partners Pty Limited

+61 2 9325 9046

www.gidynamics.com