12 May 2008

Gran Tierra Energy To Announce First Quarter 2008 Results Of Operations

Company to Host Conference Call on May 13, 2008 at 11:00 a.m. Eastern Time

CALGARY, CANADA, May 12, 2008 – Gran Tierra Energy Inc. (AMEX: GTE, TSX: GTE) today announced that the company’s senior management will discuss the company’s results of operations for the first quarter ended March 31, 2008 during a conference call scheduled for Tuesday, May 13, 2008, at 11:00 a.m. Eastern Time. The company’s financial results for the first quarter are scheduled to be released earlier that day.
What: Gran Tierra Energy Inc.’s First Quarter Results of Operations Conference Call
When: Tuesday, May 13, 2008, 11:00 a.m. Eastern
Web cast address: http://www.streetevents.comhttp://www.fulldisclosure.com

Dial-in Numbers: (888) 680-0892 (domestic) or (617) 213-4858 (international), pass code # 81399744
Contact: Al Palombo, Cameron Associates, (212) 245-8800 Ext. 209, al@cameronassoc.com

Participants may pre-register for the call at:
Pre-registrants will be issued a pin number to use when dialing into the live call which will provide quick access to the conference by bypassing the operator upon connection.
If you are unable to participate, an audio replay of the call will be available beginning two hours after the call and will be available until 11:59 p.m. on May 20, 2008, by dialing (888286-8010 (domestic) or (617801-6888 (international) using confirmation pass code 51001211. An audio replay of the call will also be available on Gran Tierra Energy’s web site, www.grantierra.com, until the next earnings call.

About Gran Tierra Energy Inc.:

Gran Tierra Energy Inc. is an international oil and gas exploration and production company operating in South America, headquartered in Calgary, Canada, incorporated in the United States, and trading on the American Stock Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company has a strategy that focuses on growing a portfolio of producing properties, plus production enhancement and exploration opportunities to provide a base for future growth. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to info@grantierra.com or 1-800-916-GTRE (4873).