The external evaluation has gained prominence in the educational landscape since 1990 and has become a tool for inducing and monitoring the operationalisation of educational reforms. In this process, the Brazilian State assumes the role of formulator, regulator and performance assessor. The National Examination of Medium Education (ENEM), established and redesigned in that context, is gradually becoming more comprehensive and widespread. Law No 13.415/2017 on the reform of medium education and with the help of the Common National Curricular Base expands its implications for basic education and higher education. Based on a desk study, the article seeks to characterise and analyse ENEM and to reveal the role it plays in shaping and consolidating a large educational market in Brazil.