Exhibit 99.1

Press Release     February 28, 2012

HollyFrontier Corporation Reports Fourth Quarter 2011 Results

Dallas, Texas, February 28, 2012 -- HollyFrontier Corporation (NYSE-HFC) (“HollyFrontier” or the “Company”) today reported fourth quarter net income attributable to HollyFrontier stockholders of $223.4 million or $1.06 per diluted share for the quarter ended December 31, 2011, compared to $14.7 million or $0.13 per diluted share for the quarter ended December 31, 2010. For the year ended December 31, 2011, net income attributable to HollyFrontier stockholders totaled $1 billion or $6.42 per diluted share compared to $104 million or $0.97 per diluted share for the year ended December 31, 2010.

For the fourth quarter, net income increased by $208.7 million, or 1,418% compared to the same period of 2010, reflecting both the effects of increased operating scale due to our recent merger and historically strong fourth quarter refining margins, which continued to benefit from wide differentials between inland and coastal-sourced crude oils. Overall refinery gross margins were $15.32 per produced barrel, a 95% increase compared to $7.87 for the fourth quarter of 2010, with overall production levels averaging 438,000 barrels per day (“BPD”) and overall crude oil charges averaging 407,000 BPD for the current quarter. The Company’s Rocky Mountain refining margins were the strongest, with average gross margins of $18.33 per barrel for the quarter. The Mid-Continent and Southwest refining operations also yielded good results, where quarterly gross margins averaged $14.71 and $14.76 per barrel, respectively.

HollyFrontier’s President & CEO, Mike Jennings, commented, “We are delighted with our fourth quarter results as we conclude our first fiscal year as a combined company. Although overall product crack spreads narrowed during the quarter as the WTI crude differentials compressed, we generated solid profits for the quarter and remained near the top of our peer group in profitability per barrel. We are especially pleased with the Company’s full year results, as this was the most profitable year in our history, with net income over $1 billion. Including last week’s special dividend declaration, we have announced special distributions to shareholders of $1.50 per share or approximately $315 million since the completion of our merger in July of last year. Further, we currently have a $350 million share repurchase program in place and continue to pay our regular quarterly dividend of $0.10 per share. Looking forward, the differentials between inland and coastal crudes are fairly robust, which should contribute favorably to our first quarter results. Further, we believe that operational synergies and increased asset scale gained during the merger will help us to extend our record of providing consistent returns and increasing shareholder value while maintaining a strong balance sheet.”

Sales and other revenues for the fourth quarter of 2011 were $5 billion, a 125% increase compared to the three months ended December 31, 2010. This increase was due primarily to the inclusion of revenues from the El Dorado and Cheyenne refineries and the effects of a 19% year-over-year increase in fourth quarter refined product sales prices. Cost of products sold for the quarter was $4.3 billion, a 114% increase compared to the fourth quarter of 2010, reflecting both the fourth quarter impact of the legacy Frontier refineries and a 13% year-over-year increase in fourth quarter crude oil acquisition costs. During the quarter, we recognized merger integration costs of $8 million, which are included among general and administrative costs. Fourth quarter cash flows from operations totaled $249.2

million, of which $122.8 million was directed towards cash dividends to shareholders. These strong cash flows continued to contribute to the Company’s combined balance of cash and short-term investments which stood at $1.8 billion on December 31, 2011 and compared to debt of $1.2 billion on a consolidated basis and $688.9 million excluding HEP debt, which is non-recourse to HollyFrontier. During the fourth quarter and for the full year ended December 31, 2011 we paid dividends of $122.8 million and $252.1 million, respectively.

The Company has scheduled a webcast conference call for today, February 28, 2012, at 11:00 AM Eastern Time to discuss financial results. This webcast may be accessed at: http://www.videonewswire.com/event.asp?id=84801.

An audio archive of this webcast will be available using the above noted link through March 12, 2012.

HollyFrontier Corporation, headquartered in Dallas, Texas, is an independent petroleum refiner and marketer that produces high-value light products such as gasoline, diesel fuel, jet fuel and other specialty products. HollyFrontier operates through its subsidiaries a 135,000 barrels per stream day (“bpsd”) refinery located in El Dorado, Kansas, a 125,000 bpsd refinery in Tulsa, Oklahoma, a 100,000 bpsd refinery located in Artesia, New Mexico, a 52,000 bpsd refinery located in Cheyenne, Wyoming and a 31,000 bpsd refinery in Woods Cross, Utah. HollyFrontier markets its refined products principally in the Southwest U.S., the Rocky Mountains extending into the Pacific Northwest and in other neighboring Plains states. A subsidiary of HollyFrontier also owns a 42% interest (including the general partner interest) in Holly Energy Partners, L.P.

The following is a “safe harbor” statement under the Private Securities Litigation Reform Act of 1995: The statements in this press release relating to matters that are not historical facts are “forward-looking statements” based on management’s beliefs and assumptions using currently available information and expectations as of the date hereof, are not guarantees of future performance and involve certain risks and uncertainties, including those contained in our filings with the Securities and Exchange Commission. Although we believe that the expectations reflected in these forward-looking statements are reasonable, we cannot assure you that our expectations will prove correct. Therefore, actual outcomes and results could materially differ from what is expressed, implied or forecast in such statements. Any differences could be caused by a number of factors, including, but not limited to, risks and uncertainties with respect to the actions of actual or potential competitive suppliers of refined petroleum products in the Company’s markets, the demand for and supply of crude oil and refined products, the spread between market prices for refined products and market prices for crude oil, the possibility of constraints on the transportation of refined products, the possibility of inefficiencies, curtailments or shutdowns in refinery operations or pipelines, effects of governmental and environmental regulations and policies, the availability and cost of financing to the Company, the effectiveness of the Company’s capital investments and marketing strategies, the Company’s efficiency in carrying out construction projects, the ability of the Company to acquire refined product operations or pipeline and terminal operations on acceptable terms and to integrate any future acquired operations, the possibility of terrorist attacks and the consequences of any such attacks, general economic conditions, our ability to realize fully or at all the anticipated benefits of our “merger of equals” with Frontier, operational and legal risks and uncertainties detailed from time to time in the Company’s Securities and Exchange Commission filings. The forward-looking statements speak only as of the date made and, other than as required by law, we undertake no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

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RESULTS OF OPERATIONS

Financial Data (all information in this release is unaudited)

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Balance Sheet Data

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Segment Information

Our operations are organized into two reportable segments, Refining and HEP. Our operations that are not included in the Refining and HEP segments are included in Corporate and Other. Intersegment transactions are eliminated in our consolidated financial statements and are included in Consolidations and Eliminations. The Refining segment includes the operations of our El Dorado, Tulsa, Navajo, Cheyenne and Woods Cross refineries and NK Asphalt Partners (“NK Asphalt”). Refining activities involve the purchase and refining of crude oil and wholesale and branded marketing of refined products, such as gasoline, diesel fuel and jet fuel. These petroleum products are primarily marketed in the Mid-Continent, Southwest and Rocky Mountain regions of the United States. Additionally, the Refining segment includes specialty lubricant products produced at our Tulsa refinery that are marketed throughout North America and are distributed in Central and South America. NK Asphalt operates asphalt terminals in Arizona and New Mexico.

The HEP segment involves all of the operations of HEP. HEP owns and operates a system of petroleum product and crude gathering pipelines in New Mexico, Oklahoma, Texas and Utah, distribution terminals in Arizona, Idaho, Kansas, New Mexico, Oklahoma, Texas, Utah, Idaho, Washington and Wyoming and refinery tankage in Kansas, New Mexico, Oklahoma, Utah and Wyoming. Revenues are generated by charging tariffs for transporting petroleum products and crude oil through its pipelines, by leasing certain pipeline capacity to Alon USA, Inc., by charging fees for terminalling refined products and other hydrocarbons, and storing and providing other services at its storage tanks and terminals. The HEP segment also includes a 25% interest in SLC Pipeline LLC (“SLC Pipeline”) that services refineries in the Salt Lake City, Utah area. Revenues from the HEP segment are earned through transactions with unaffiliated parties for pipeline transportation, rental and terminalling operations as well as revenues relating to pipeline transportation services provided for our refining operations.

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Refining Operating Data

Our refinery operations include the El Dorado, Tulsa, Navajo, Cheyenne and Woods Cross refineries. The following tables set forth information, including non-GAAP performance measures about our consolidated refinery operations. The cost of products and refinery gross margin do not include the effect of depreciation and amortization. Reconciliations to amounts reported under GAAP are provided under “Reconciliations to Amounts Reported Under Generally Accepted Accounting Principles” below.

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