The relationship between leisure-time physical activity and diabetes complications was examined in 628 individuals with insulin-dependent diabetes mellitus. Neuropathy was based upon clinical exam; retinopathy by fundus photographs; nephropathy by urine samples and macrovascular disease by clinician diagnosis. Past week physical activity was found to be inversely related to complication status but since current inactivity could be the result of the complications, historical activity (estimated leisure activity during ages 14-17) was also examined in relation to complication status. Males reporting higher levels of historical physical activity had a significantly lower prevalence of nephropathy and neuropathy but not retinopathy as demonstrated by multivariate analysis (controlling for duration of disease, age, and current activity levels). The lack of similar findings in women may be due to their low levels of reported physical activity. The consistent relationship between historical leisure physical activity and development of complications in males suggests that activity may be protective or at least not detrimental to the individual with insulin-dependent diabetes.