The study explores and describes South African school children's perspectives of HIV and AIDS, and links this to their respective cognitive developmental stage. The paper highlights developmental differences in the children's perceptions of HIV or AIDS and makes specific recommendations for improving HIV/AIDS education in school. A questionnaire of mainly open-ended questions was used to survey the HIV/AIDS-related perceptions of 1 904 school-going children aged 6 to 19 years. In-depth content analyses as well as basic statistical analyses were performed on the data. Although the school children had a good basic knowledge of HIV/AIDS and generally positive attitudes towards HIV and AIDS, they believed many misconceptions and myths. The children were mostly very afraid of HIV or AIDS and felt extremely vulnerable to HIV infection. The particular developmental phase was the strongest predictor of a child's understanding of HIV/AIDS. The findings have been used to formulate guidelines for the development or enhancement of age-appropriate HIV/AIDS education programmes or curricula in schools. It is hoped that teachers, educators and youth workers will use these findings to re-evaluate and adjust their HIV/AIDS education programmes and messages to fit the needs of the young people in their care.