The knowledge of and attitude to acquired immunodeficiency syndrome (AIDS) of 738 secondary school youths in Calabar were studied by questionnaire in March 1991. Most (92%) of the adolescents had heard about AIDS, largely through the mass media (79-85%), with parents and teachers contributing in less than 40%. About 30% did not know that AIDS exists in Nigeria. Most of them knew that promiscuity, blood transfusion and sharing injection needles and syringes are the major modes of transmission, but a number still incriminate toilet seats, eating utensils, hand-shaking and kissing. Only 31% were aware that condoms provide protection. For self-protection the youths prefer abstinence (45%) and confinement to one sex partner (19%). Only 3.6% would adopt the use of condoms. To prevent the spread of AIDS, the youths prescribe isolation (37%), treatment (34%), and killing (14%) of diagnosed cases. Most youths (77%) will stop seeing friends and 63% will reject relatives who develop AIDS. The study reveals that while general awareness of AIDS is fairly good, detailed knowledge is riddled with misconceptions and confusion. It is recommended that physicians in the community should assist in disseminating accurate information, with the support of parents, teachers and the youths themselves.