This paper aims to address and analyze the environmental issues related to the Brazilian bidding rounds for exploration and production of oil and natural gas held by the National Petroleum Agency (ANP) from 1999 to 2005. To do so, after a brief retrospective of the seven rounds, the four main points of the bidding process are analyzed from an environmental perspective: the selection criteria for choosing the areas to be offered, the Minimum Exploration Program required by ANP, the eligibility criteria for the oil companies to take part of the bids and the concession agreements. Thus, it is possible to present the evolution of the environmental component insertion from the first to the seventh bidding round, and then to assess its efficiency in each round, apart from offering suggestions for its improvement. The suggestions presented are based oil the related international experience and oil the lessons learned during the last seven years. (c) 2006 Elsevier Ltd. All rights reserved.