The study assessed levels of knowledge and sources of information on HIV/AIDS among secondary school students in Osun State, Nigeria. Multistage, random sampling was used to identify 592 students from 5 local areas in Osun State. A self-administered questionnaire revealed that 50% of students believed one could contract HIV through mosquito bites and 53.7% through kissing. Half of the students believed that someone with HIV/AIDS can look healthy; 92.6% had heard of HIV/AIDS prior to the study and 29.4% believed there was a cure for AIDS. The greatest source of information was the media, with traditional healers being the least important source. Greater involvement of schools and public libraries in HIV education and information dissemination is recommended.