From the Law nº 9,074, issued in 1995, the Brazilian electrical sector experienced the starting of a reform in its institutional framework. Following an international trend, this law introduced the competition in the generation and commercialization areas, as well as started the privatization process of the distribution companies. In the following year, the electrical sector regulatory agency was created. In 1998, as a result of the Electrical Sector Restructuring Project (RE-SEB), the Law nº 9,648 set the Wholesale Energy Market, e a new type of agent emerged - the trading companies. Besides that, this law created the Independent System Operator. Therefore, without analyzing how efficient it was, one can state that in the institutional framework introduced by the RE-SEB Project, the issues related with system operation and energy trading were well defined. On the other hand, the expansion planning aspects were neglected and left to be discussed and detailed in a second phase, which did not take place. Actually, a change on the institutional arrangement that supported the expansion planning activities was introduced: The Electrical System Planning Coordination Group (GCPS), chaired by ELETROBRÁS, was replaced by the Electrical System Expansion Planning Coordination Council (CCPE), now under the MME. Also, the generation expansion planning became indicative. These changes, associated to the irregularity of the staff in charge of the planning studies, led to the decrease of the effectiveness of this important function in the last years. However, the new institutional framework put in place in 2004 with the Laws no. 10,847 (establishment of Empresa de Pesquisa Energética - EPE) and 10,848 (New Energy Trading Law) promoted the renovation of this very import integrating function, which is now in a consolidation phase. This work has two basic objectives: describe the main aspects of the electrical sector legal framework, analyzing the several laws and decrees and their updating, highlighting the new institutions and the important function of the expansion planning; and (ii) analyze the issue of the energy planning in the new institutional framework, with emphasis in the electrical sector, stressing the roles of the institutions involved in the planning process, the implementing phases, the interface between the electrical sector and the other energy sectors, as well as the technical, economic and methodological aspects associated to the short (10 years) and long (30 years) term planning horizons.