Sexuality is embedded in a social and cultural origin and its approach must go beyond biological aspects. Questionnaire on Sex Education in Schools (QUSES) assesses the knowledge, comfort, motivation and involvement of teachers in relation to sex education. This article aims to culturally adapt and verify the reliability of QUSES. The Experts Committee realized the Cultural adaptation and content validation. The Cronbach's alpha and its stratification were tested for reliability. It was applied to 100 teachers with an average of 44.45 (9.62) years of age. Words and phrases were modified, maintaining the equivalences of the original version. Question of knowledge was the most modified due to regulatory differences between countries. Reliability data was similar to the original instruments and were considered good. The lowest values were α = 0.741 for subscale of efficacy of results, α = 0.812 and α = 0.849 for subscale of involvement (cognitive). QUSES was culturally adapted for Brazilian elementary schools teachers presenting good reliability. It is relevant, because it evaluates sex education fully and may support in implementation and monitoring public policies related to health promotion in schools.