Our paper presents a study on the National Examination of High School Education created in 1998 by the MEC to assess the skills and abilities developed by High School students. We stand here, from data and official documents, research with high school teachers and extensive bibliography, that at first ENEM aimed to be an instrument of government to force a national core curriculum, trying to have the quality of education via the evaluation instrument being like this the regulation of quality. The evaluation system of MEC since its inception, aimed to be the instrument for curriculum changes in High School according to the concept of a changing world, demanding new skills and competencies. One begins the process of the first national exam as a way to correct and guide the curricula of middle schools by creating new demands for knowledge through the national evaluation. Its regulatory function, however, started missing its target when schools discovered ways to prepare for the exam in extra moments to the classroom. The senseless competition among schools, among institutions, among educational systems took place. The training for taking the exam ended the initial characteristics of regulation of quality.
secondary education; ENEM; High School curriculum