This study provides nationally representative data on knowledge, attitudes and practices of secondary students in years 10 and 12 concerning HIV / AIDS and related diseases. A national sample of 3550 students from 118 schools participated in the study. The survey is a follow-up and extension of the survey carried out in 1992 by the National Centre in HIV Social Research (Dunne et al. 1993). For the first time in Australia, we are able to document change over time at a national level in young people's HIV /STD-related knowledge, attitudes and practices.