The purpose of this paper is to present the main aspects of the state of São Paulo legislation conceming environmental impact assessment and the respective report and to call anention to some new alterations that mean considerable progress in order to make flexible the utilization of this important instrument of environmental policy. These changes permit to simplify the procedure for evaluating environrnental impact for small and medium projects and simultaneously avoid making it banal. Furthermore, these changes reaffirm the importance of the involvement of community groups and non-govemmental organizations in this procedure. Finally, this article brings a brief guide to help elaborate the preliminary environmental report, the first step in the new procedure, according to the state of São Paulo legislation.Apresentação dos principais aspectos da legislação do estado de São Paulo referentes ao estudo prévio de impacto ambiental e de seu respectivo relatório (EIAlRima). Recentes mudanças que representam um avanço considerável no sentido de flexibilizar a utilização desse importante instrumento de política ambiental.