To determine whether flavonoid intake explains differences in mortality rates from chronic diseases between populations. DESIGN: Cross-cultural correlation study. SETTING/PARTICIPANTS: Sixteen cohorts of the Seven Countries Study in whom flavonoid intake at baseline around 1960 was estimated by flavonoid analysis of equivalent food composites that represented the average diet in the cohorts. MAIN OUTCOME MEASURES: Mortality from coronary heart disease, cancer (various sites), and all causes in the 16 cohorts after 25 years of follow-up. RESULTS: Average intake of antioxidant flavonoids was inversely associated with mortality from coronary heart disease and explained about 25 f the variance in coronary heart disease rates in the 16 cohorts. In multivariate analysis, intake of saturated fat (73 P = 0.0001), flavonoid intake (8°P = .01), and percentage of smokers per cohort (9 P = .03) explained together, independent of intake of alcohol and antioxidant vitamins, 90 f the variance in coronary heart disease rates. Flavonoid intake was not independently associated with mortality from other causes. CONCLUSIONS: Average flavonoid intake may partly contribute to differences in coronary heart disease mortality across populations, but it does not seem to be an important determinant of cancer mortality.