The aim of this study was to analyze the content of STIs in the didactic collections of Biology of 2018 recommended by the National High School Textbook Program (NHSTP) of the Ministry of Education. Eight didactic collections of biology of NHSTP were selected and analyzed. The methodology of the study was thematic content analysis, with the definition of five categories a priori: location of the theme; structure and formatting; content; language and visual resources that were divided into criteria and subcriteria. The other books evaluated did not address the subject to the satisfaction, being flawed/superficial, which shows that the theme STIs can still be better explored in some biology textbooks in high school. Therefore, it is still important to encourage teachers to explore the subject better with their students, going beyond textbooks. Thus, the study concluded that most of the high school books recommended by NHSTP do not address the theme STIs effectively, generating the need for complementary didactic planning by teachers in order to broaden the debate on this subject in the classroom.