OBJECTIVE: To study whether physical activity is associated with reduced occurrence of asymptomatic leg atherosclerosis. DESIGN: Longitudinal and cross-sectional analyses of the population-based cohort "men born in 1914". METHODS: Comparison of the systolic ankle/arm pressure index (AAI) at age 68 in groups who were sedentary, performed some activity, and performed regular physical training at 55 and 68 years of age. RESULTS: At 55 years of age, 100 (27%) were sedentary, 209 (58%) reported some physical activity and 54 (15%) reported regular physical training. At 68 years, 194 men (53%) reported the same degree of physical activity, 127 (35%) reported a higher physical activity, and 42 (12%) reported lower physical activity. Physical activity at 55 years (p =0.03) and increased physical activity between 55 and 68 years (p =0.03) were both associated with higher AAI at 68 after adjusting for potential confounders. At 68 years, AAI was 0.89+/-0.21, 1.01+/-0.13 and 1.05+/-0.11, respectively, in men who were sedentary, reported some physical activity, and regular physical training (p =0.0002). This association remained significant after adjustments for potential confounders. CONCLUSIONS: regular physical activity is associated with reduced occurrence of asymptomatic leg atherosclerosis, even in men taking up exercise after age of 55.