A study on sexual behaviour and knowledge of HIV risk was undertaken amongst 511 male students in Zimbabwe. The study was conducted amongst pupils aged 11 to 19 years drawn from urban and rural secondary schools using a self-administered questionnaire. Thirty seven pc of the students reported that they had experienced sexual intercourse, with up to 63 pc reporting having had more than one partner. Twenty one pc of boys aged 12 years reported having had intercourse and the proportion increased with age. Knowledge about AIDS was high (93 pc) with up to 75 pc of the boys reporting that they received the information through the media and only 31 pc got it from their teachers. Logistic regression used to analyse reasons for variation in HIV/AIDS knowledge and of modes of its transmission determined that educational level, actual school attended, access to information from magazines and educational aspirations were significant predictors (p values = 0,005) of knowledge. Individual risk assessment was higher amongst students who reported sexual experience (p = 0,0001). Sixty pc of the sexually experienced boys reported having used condoms. Six pc of the boys reported having intercourse with a commercial sex worker and of these, 85 pc used condoms. Compared with previous studies there appeared to be a reduction in high risk behaviours amongst male secondary school students. However, there is need for increased HIV preventive information through school educational programmes, as increase and variation in HIV information and modes of transmission was seen depending on access to information.