HIV/AIDS knowledge and health-related attitudes and behaviors among deaf and hearing adolescents in southern Brazil are described. Forty-two deaf students attending a special nonresidential public school for the deaf and 50 hearing students attending a regular public school, ages 15-21 years, answered a computer-assisted questionnaire. (There was simultaneous video translation of questions to Brazilian Sign Language.) A branched decision-tree structure was used to determine level of sexual experience and hearing status. Deaf participants scored lower on HIV/AIDS knowledge, demonstrating a need to improve school-based instruction and develop campaigns tailored to this group's requirements. Though the hearing students reported more sexual activity than the deaf students, no other significant differences were found in health-related attitudes and behaviors. Two findings of concern are the high rate of sexual abuse reported by deaf participants and the large number of deaf adolescents reporting having a friend with AIDS.