CALGARY, Canada, November 29, 2007 - Gran Tierra Energy Inc. (OTC Bulletin Board: GTRE), a company focused on oil exploration and production in South America, today announced that the company has initiated field operations in Blocks 122 and 128 in northern Peru.

Blocks 122 and 128 are both exploration blocks that were awarded to Gran Tierra Energy in 2006. These two blocks are on the eastern flank of the prolific Mara~non Basin where over one billion barrels of recoverable oil has been discovered to date. Block 122 encompasses approximately 1.2 million acres and Block 128 encompasses approximately 2.2 million acres of land. Gran Tierra Energy is Operator and holds a 100% working interest in both blocks.

Approximately 20,000 linear kilometers of new high definition gravity and magnetic data is scheduled to be acquired over the entirety of Blocks 122 and 128 in the coming three months to fulfill the company's work program commitments for the First Exploration Period of each block. This data will be used to define exploration leads over which 2-D seismic data will be acquired in the Second Exploration Period of each block. The Second Exploration Periods for both blocks begins in the second quarter of 2008.

Dana Coffield, President and CEO, stated "With the onset of our operations in Peru, Gran Tierra Energy has begun maturing a vast land position to identify high impact leads and prospects for future drilling. Our lands in Peru are located immediately adjacent to an extremely prolific petroleum basin but have never been tested by drilling. In addition, Peru has one of the most attractive fiscal regimes in Latin America. This exploration program complements our ongoing reserve and production growth that has been achieved through our exploration drilling operations in Colombia and Argentina in 2007."

About Gran Tierra Energy Inc.

Gran Tierra Energy Inc. is an international oil and gas exploration and production company, headquartered in Calgary, Canada, incorporated and traded in the United States and operating in South America. Gran Tierra Energy holds interests in producing and prospective properties in Argentina, Colombia and Peru. The company strategy is focused on establishing a portfolio of drilling opportunities to exploit undeveloped reserves to grow production, as well as undertaking exploration to grow future reserves. Additional information concerning Gran Tierra Energy is available at www.grantierra.com. Investor inquiries may be directed to [email protected] or 1-800-916-GTRE (4873).

Forward Looking Statements

The statements in this press release regarding Gran Tierra Energy's expectations regarding the amount and timing of data to be acquired in Blocks 122 and 128, as well as the uses to which the data will be put, are 'forward-looking statements' within the meaning of Section 27A of the United States Securities Act of 1933, as amended, and Section 21E of the United States Securities Exchange Act of 1934. Although these forward-looking statements reflect the good faith judgment of management, forward-looking statements are inherently subject to known and unknown risks and uncertainties that may cause actual results to be materially different from those discussed in these forward-looking statements including, but not limited to, in the case of these forward-looking statements, unexpected delays in field operations to acquire the data due to equipment failure or other unforeseen reasons; unforeseen events, such as unexpected difficulties in drilling or unexpected discoveries, may cause Gran Tierra Energy to reallocate resources, which may delay field operations to acquire the data in Blocks 122 and 128; and unexpected costs may decrease funds available to carry out Gran Tierra Energy's plans described in the press release, which could delay or prevent execution of these plans. Readers are urged not to place undue reliance on these forward-looking statements, which speak only as of the date of this release. Gran Tierra Energy assumes no obligation to update these forward-looking statements to reflect any event or circumstance that may arise after the date of this release, other than as may be required by applicable law or regulation. Readers are urged to carefully review and consider the various disclosures, including the risk factors, made by Gran Tierra Energy in its reports filed with the Securities and Exchange Commission, in particular its quarterly report on Form 10-Q filed on November 8, 2007, which attempt to advise interested parties of the risks and factors that may affect Gran Tierra Energy's business. If one or more of these risks or uncertainties materialize, or if the underlying assumptions prove incorrect, Gran Tierra Energy's actual results may vary materially from those expected or projected.