To study reproductive health knowledge, attitudes and practices of youth in the Islamic Republic of Iran, 1111 university students completed a questionnaire with 43 closed questions. The overall mean knowledge score was 54%. Knowledge of males and females, and of married and single students, was similar. Of 664 students answering questions about reproductive health behaviour, 54 (8%) reported having sexual intercourse before marriage; 16% of males and 0.6% of females; 48% of them had used condoms. The majority of students believed that the risk of AIDS and other sexually transmitted infections was moderate but that youth had a low ability to practise healthy behaviour. The majority believed in the benefits of reproductive health knowledge for youth but felt that services were inadequate.