To examine sex-specific associations between sports activities in leisure time and incident myocardial infarction (MI) in a representative population sample in Germany. DESIGN: Cohort study. METHODS: The study was based on 3501 men and 3475 women (aged 45-74 years) who participated in one of the three MONICA Augsburg surveys between 1984 and 1995 and were followed up until 2002. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated from Cox proportional hazard models. RESULTS: A total of 295 cases of incident MIs among men and 91 among women were registered during a median follow-up period of 8.6 years. In both sexes, moderate and high level of sports activities in leisure time were associated with a reduced risk of incident MI after age and survey adjustment; the HRs of MIs associated with a moderate and high level of sports activities in leisure time were 0.68 (0.49-0.96), and 0.71 (0.50-0.99) for men and 0.42 (0.21-0.84), and 0.18 (0.04-0.74) for women. Further adjustment for other major coronary heart disease risk factors attenuated the HRs: in moderately and highly active men, the HRs were not significant anymore (HRs 0.78 and 0.84, respectively), but the HRs remained significantly reduced in moderately and highly active women (HR 0.49; 95% CI, 0.24-1.00 and HR 0.21; 95% CI, 0.05-0.87, respectively). CONCLUSION: Moderate or high levels of sports activities in leisure time are associated with a significantly reduced risk of MI in women, but not men from the general population.