Knowledge of dangers of sexual promiscuity was assessed in 2 institutions of higher learning. The objectives were to find out the knowledge of medical and social consequences as well as the factors responsible for sexual promiscuity among Nigerian youths. The study also assessed the discrepancies in societal concept of sex norms for males and females. The result was used as an index to determine the need for sex education for Nigerian youths. A total of 200 students (100 from each school) was assessed by random selection and use of a questionnaire. The result showed that students had a fair knowledge of sexual promiscuity, although in terms of medical consequences the knowledge was low for both groups. On social consequences, the knowledge was fair for both groups. Students agreed that lack of financial support and of supervision from parents and teachers were among the causes of sexual promiscuity. Recommendations were made for Health Education in these areas in institutions of higher learning. Also, recommendations were made for parental education on how to bring up, and care for, their adolescents to reduce the problems of sexual promiscuity. It was also recommended that a compulsory course on sexual promiscuity should be included in the syllabus in institutions of higher learning.