The work seeks to understand the role of Brazilian Congress in foreign policy, between 1985 and 2005, specially with regards to its attributions in the treaty-making process. As we reflect about this theme, we face inevitably the common sense idea which suggests us that Brazilian legislative branch action concerning foreign policy would be simply reduced to the automatic approval of international acts, negotiated by the Executive with ample and total discretionarity. This perception was developed from the formal institutional diminished competence of Brazilian Congress on the subject, based on the ex post approval of international agreements, in the face of the Executive power in defining foreign policy. Despite the inequality between the two attributions, the role of the legislative branch still needs to be analysed more seriously. Therefore, this direct and formal little attribution would make possible for the members of Congress to increase their influence over the decision- making process of Brazilian foreign policy.