The relationship between the school environment and health has infrequently been examined. This study sought to examine the association between school students' perceptions of their school environment, teachers' and peers' support and their health behaviours. A cross sectional descriptive survey by supervised self-administration was conducted in 1996 based on the international WHO collaborative survey of school children's health and lifestyle (the HBSC Study) and extended in an Australian setting. Randomly sampled primary and secondary schools from Catholic, Independent and Government education sectors throughout New South Wales (NSW), Australia, were invited to participate. The final sample included 3918 school students attending Year 6 (primary school), Year 8 and Year 10 (high school) from 115 schools. The main outcome measures were self-reported health status and 7 health behaviours (tobacco use, alcohol use, physical activity, dental hygiene, nutritional intake, seat belt and bicycle helmet use). Independent variables included student perceptions of the school environment, perceptions of teachers' and peers' support. Girls, Year 6 students and students who have less than $19 a week to spend were significantly more likely to have positive perceptions towards their school environment, teacher(s) and peers. Students who had positive perceptions regarding their school environment and perceived their teachers as supportive were significantly more likely to engage in health promoting behaviours adjusting for age, sex and average weekly pocket money. A supportive peer environment was not associated with positive health behaviour. Health promotion practitioners need to consider the impact of the school environment on health behaviours of school students. In particular, practitioners should consider intervention models that improve the school environment as a key strategy within a health promoting school.