The relations of dietary antioxidants vitamin C and beta-carotene to 30-year risk of stroke incidence and mortality were investigated prospectively in the Chicago Western Electric Study among 1,843 middle-aged men who remained free of cardiovascular disease through their second examination. Stroke mortality was ascertained from death certificates, and nonfatal stroke from records of the Health Care Financing Administration. During 46, 102 person-years of follow-up, 222 strokes occurred; 76 of them were fatal. After adjustment for age, systolic blood pressure, cigarette smoking, body mass index, serum cholesterol, total energy intake, alcohol consumption, and diabetes, relative risks (and 95% confidence intervals) for nonfatal and fatal strokes (n = 222) in highest versus lowest quartiles of dietary beta-carotene and vitamin C intake were 0.84 (0.57-1.24) and 0.71 (0.47-1.05), respectively. Generally similar results were observed for fatal strokes (n = 76). Although there was a modest decrease in risk of stroke with higher intake of beta-carotene and vitamin-C intake, these data do not provide definitive evidence that high intake of antioxidant vitamins decreases risk of stroke.