Market Price: $0.15

    Market Price: $0.12

May 17, 2011

Excelsior Mining Corp. (TSX-V: MIN) (Frankfurt: 3XS) (“Excelsior”) is pleased to announce additional assay results from the drill program on the Gunnison Copper Property located within the copper porphyry belt in southern Arizona. Highlights include:

Drill Hole From (feet) To (feet) Length (feet) Total Copper %
NSD – 13 790.0 1590.0 800.0 0.34
including 790.0 1360.0 570.0 0.42
NSD – 10 561.5 1390.0 828.5 0.38
NSD – 05 674.5 1130.0 455.5 0.38
NSD – 02 605.0 1550.0 945.0 0.27

Note: Holes not drilled in sequence.

“These latest assay results continue to demonstrate long intervals of highly-fractured mineralized core of ample grade,” says Stephen Twyerould, President and CEO of Excelsior. “With the drilling now completed, we remain confident that the objectives of this program will be met and that we will be able to move the majority of our current copper resource from the inferred to the indicated category."

Complete assay highlights with drill plan map are posted on the Excelsior website at:http://excelsiormining.com/e/gunnison.php. The drill program is now completed with a total of 33,792 feet of drilling in 20 holes. Gunnison currently contains a National Instrument (NI) 43-101 compliant inferred resource of 4.77 billion pounds of copper (787 million tons at 0.30% copper) which remains open for expansion (see news release dated November 2, 2010). An upgraded resource estimate is expected at the end of the second quarter of 2011.

All samples are prepared from manually split half-core sections on site in Arizona. Split drill core samples are then sent to Skyline Assayers & Laboratories in Tucson, Arizona for Total Copper and Sequential Copper analyses. Standards, blanks, and duplicate assays are included at regular intervals in each sample batch submitted from the field as part of an ongoing Quality Assurance/Quality Control Program.

Excelsior's exploration work on the Gunnison Property is supervised by Stephen Twyerould, Fellow of AUSIMM, President and CEO of Excelsior and a Qualified Person as defined by NI 43-101. Mr. Twyerould has reviewed and is responsible for the technical information contained in this news release. Mr. Twyerould has verified the data disclosed in this news release, including sampling, analytical and test data underlying the information disclosed in this news release. Mr. Twyerould has verified that the results were accurate from the official assay certificates provided to Excelsior.

About Excelsior

Excelsior is an exploration and development company with a copper project located within the copper porphyry belt of Arizona. The Gunnison Copper Project is located close to the required infrastructure and with its in-situ recovery potential, is intended for near-term production. The Excelsior team consists of experienced professionals with proven track records of advancing projects towards production.

Further details about Excelsior can be found at: http://www.excelsiormining.com. Further information about the Gunnison Copper Project can be found in the technical report filed on SEDAR at www.sedar.com entitled: Gunnison Copper Project, Cochise County, Arizona, USA, Mineral Resource of the North Star and South Star Deposits dated June 2010.


"Stephen Twyerould"
President & CEO

T: 604-681-8030
F: 604-681-8039

Renmark Financial Communications Inc.
Barry Mire: This email address is being protected from spambots. You need JavaScript enabled to view it.
Lyane Bourassa: This email address is being protected from spambots. You need JavaScript enabled to view it.
Tel.: (514) 939-3989 or (416) 644-2020

Information set forth in this news release may involve forward-looking statements under applicable securities laws. Forward-looking statements are statements that relate to future, not past, events. In this context, forward-looking statements often address expected future business and financial performance, and often contain words such as "anticipate", "believe", "plan", "estimate", "expect", and "intend", statements that an action or event "may", "might", "could", "should", or "will" be taken or occur, or other similar expressions. All statements, other than statements of historical fact, included herein including, without limitation; statements about the production potential of the Gunnison Copper Project are forward-looking statements. By their nature, forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause our actual results, performance or achievements, or other future events, to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. Such factors include, among others, the following risks: the need for additional financing; operational risks associated with mineral exploration; fluctuations in commodity prices; title matters; environmental liability claims and insurance; reliance on key personnel; the potential for conflicts of interest among certain officers, directors or promoters with certain other projects; the absence of dividends; competition; dilution; the volatility of our common share price and volume and the additional risks identified the management discussion and analysis section of our interim and most recent annual financial statement or other reports and filings with the TSX Venture Exchange and applicable Canadian securities regulations. Forward-looking statements are made based on management's beliefs, estimates and opinions on the date that statements are made and Excelsior undertakes no obligation to update forward-looking statements if these beliefs, estimates and opinions or other circumstances should change, except as required by applicable securities laws. Investors are cautioned against attributing undue certainty to forward-looking statements.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release, and no securities regulatory authority has either approved or disapproved of the contents of this release.










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