As the world energy scenario becomes more competitive and turbulent, especially in the case of the oil and gas industry, strategic alliances and networks have been increasingly established to enter new markets, diversify firm portfolio and maximize company`s capacity and performance. The objective of this dissertation is to evaluate the strategic implications of alliances and networks in the case of the International Unit of Petrobras, considering the current economic scenario and new perspectives for the world industry of oil and gas, after the institution of the Law 9.478 (1997) in Brazil, that opened the national oil and gas market and forced Petrobras into international markets. This study focuses on Petrobras, the largest Brazilian company and ranked 12nd among firms in the international energy industry, in greater part because of its internationalization process and desire to sustain its national competitive advantage, by way of strategic alliances. Data for the study was collected making use of a large public database from fiscal entities, daily newsletters and websites, especially from Petrobras. In addition to documental research and with the help of a semi-structured questionnaire, a survey helped collect data regarding the perceptions of Petrobras-ANI`s main executives` on the importance of alliances and networks for Petrobras-ANI`s strategy. The analysis of the strategic implications of Petrobras-ANI`s association in alliances for its businesses was conducted with the help of a set of analytical tools developed by Macedo-Soares to carry out strategic analysis from a relational perspective, i.e., taking into account firm relationships and the networks formed by these.