We assessed the sexual behavior patterns of 368 unmarried, sexually active adolescent boys (294 rural, 74 urban) and their knowledge of sexually transmitted diseases (STDs) and correct use of condoms. The mean knowledge score for STDs was low and significantly associated with educational level (p < .0001). The mean awareness score for correct use of condoms was 0.42 on a scale of 10 and significantly associated with employment status and age at first coitus (p < .001). There was a negative correlation (-0.17) between literacy and knowledge of correct use of condoms. Selection of the first sexual partner, usually a prostitute, was influenced by employment status, age at first coitus, and literacy level. These data suggest that sexually active adolescent boys in Gujarat, India are inadequately prepared to protect themselves against STDs and, therefore, that it is imperative to impart to them some knowledge of safe sex.