A wide institutional and market reorganization derived from the privatizations of public services concessions in Brazil in economic sectors. It became evident an increasing need to establish business management actions in order to produce the expected performance from those concessions. Embbeded in uncertainties, regulated sectors like piped gas distribution have been underestimated by researchers in respect of strategic management issues. The present research focused, under integrative and relational perspectives, the effect of the environmental factors to the performance of CEG and CEG RIO - gas distribuiton companies in Rio de Janeiro State, privatized in july, 1997. According to Yin´s case study methodology, a triangulation of methods was adopted. Therefore, data was collected through documental/telematized investigation, survey of management perceptions using a mostrly structured questionnaire and complementary interviews. The interpretation and analysis of data were based on the appropriate theoretical reference aided by the generic integrative and the relational models from Macedo-Soares (2000 e 2002). The results highlighted a strategic fit by the companies, although environmental factors could be more strategically oriented. Despite the establishment of alliances not being a strategic practice, the relational perspective added value to the traditional perspective, contributing with new insights to the companies´ strategic decision making processes. The study also brought contributions to the mentioned strategy analysis models and to the management of public services concessions.