To assess parents', teachers' and students' knowledge of sex education and their level of acceptance of its introduction into the school curriculum in Nigeria, questionnaires were sent to teachers, students and parents of eight secondary schools located within Ile-Ife town. The responses of individual groups were collated, analysed and compared. A total of 1000 respondents (400 students, 400 parents and 200 teachers) returned the completed questionnaires. All the teachers and parents and 60% of the students had heard of sex education. A majority of the parents (92%), teachers (90%) and students (78%) supported its introduction into the school curriculum and believed that it would prevent unwanted pregnancies, enhance healthy relationships between opposite sex, prevent transmission of HIV infections and STDs, provide the knowledge of sexual interactions, consequences and responsibilities and to educate the students on the basic processes of human reproduction. One hundred and fifty-four (15.4%) of the respondents opposed the introduction of sex education because they believed that it would corrupt the students, it might lead to experimentation and that it should be the responsibility of the parents at home. Adolescent sex education should be incorporated into Nigerian schools. It is probably the most cost-effective intervention that could be made to ensure the future reproductive health of the Nigerian community.