BACKGROUND: The relationship between parental physical activity and children's physical activity and cardiorespiratory fitness has not been well studied in the Australian context. Given the increasing focus on physical activity and childhood obesity, it is important to understand correlates of children's physical activity. This study aimed to investigate whether parental exercise was associated with children's extracurricular sports participation and cardiorespiratory fitness. METHODS: The data were drawn from a nationally representative sample (n = 8,484) of 7-15 year old Australian schoolchildren, surveyed as part of the Australian Schools Health and Fitness Survey in 1985. A subset of 5,929 children aged 9-15 years reported their participation in extracurricular sports and their parents' exercise. Cardiorespiratory fitness was measured using the 1.6 km (1-mile) run/walk and in addition for children aged 9, 12 or 15 years, using a physical work capacity test (PWC170). RESULTS: While the magnitude of the differences were small, parental exercise was positively associated with children's extracurricular sports participation (p < 0.001), 1.6 km run/walk time (p < 0.001) and, in girls only, PWC170 (p = 0.013). In most instances, when only one parent was active, the sex of that parent was not an independent predictor of the child's extracurricular sports participation and cardiorespiratory fitness. CONCLUSION: Parental exercise may influence their children's participation in extracurricular sports and their cardiorespiratory fitness levels. Understanding the correlates of children's extracurricular sport participation is important for the targeting of health promotion and public health interventions, and may influence children's future health status.