The objective of this dissertation is to evaluate the planning model developed at PETROBRAS, focusing its evolution and structure. With this aim, some planning methodologies are described, in order to create a theoretical framework that can provide basic criteria to evaluate the planning process adopted by the Company. Next, the results of a case study carried out at this Company are presented,describing the evolution of the Strategic Planning process, the power relations and the actors involved in this process and their responsibilities. Finally, some proposals,based on the theory discussed and appropriate to the observed reality are presented, aiming at improving the Planning Process.