Resumo. ABSTRACT The relative age effect (RAE) is a phenomenon that provides participation and performance advantages to athletes born in the first months of the year compared to other athletes within the same age category. The aim of the study was to investigate the effects of relative age in the in the major leagues of Brazilian basketball: Liga de Desevolvimento do Basquete (LDB), Liga de Basquetebol Feminino (LBF) and the Novo Basquete Brasil (NBB) considering the geographic region, the final classification of the teams, and the career period. The sample consisted of 831 athletes from the main leagues of Brazilian basketball during the 2014-2015 season. Information for the survey was obtained from the Brazilian Basketball Confederation website (www.cbb.com.br) and the National Basketball League website (www.lnb.com.br). The RAE was found in the Southeast and South LDB teams and in the Southeast NBB teams, and was not related to the teams' final classification. In addition, the RAE was reversed in the career consolidation phases of NBB athletes. We conclude that the RAE is present in LDB and NBB basketball players. An inverse RAE is observed in athletes aged 25-34 years, and there is an absence of this phenomenon in athletes who are at the final phase of their career.