In this paper is analyzed some aspects of the deregulated Peruvian electric power system with emphasis on transmission services and congestion problems in the operation and planning. The deregulation process of the Peruvian electric sector was started in 1992 when it was enacted the Electric Concessions Law (LCE). The LCE and its Rules separates the activities of the electric sector in generation, transmission and distribution. According to the LCE the generation sector is competitive while the transmission system, which is composed by the main and secondary systems, is defined as a private monopoly regulated by the Energy Tariffs Commission. In despite of the relative success in the generation and distribution sectors, in the transmission sector the open access rules and the prices signals for the transmission expansion have originated some controversies between the participant agents of the electricity market, some of them will be considered in this work. © 2001 IEEE.