Since 1965, the Honolulu Heart Program has followed up 8,006 men in a prospective study of cardiovascular disease. Of those subjects free of stroke at the time of study entry, 2,916 were classified as nondrinkers of alcohol and 4,962 as drinkers. In 12 years of follow-up, 197 drinkers and 93 nondrinkers experienced a stroke. No significant relationships were noted between alcohol and thromboembolic stroke. When compared with nondrinkers, however, the risk of hemorrhagic stroke more than doubled for light drinkers and nearly tripled for those considered to be heavy drinkers. These findings are statistically significant and independent of hypertensive status and other risk factors. Results further indicate that alcohol has a greater effect on hemorrhagic strokes that are subarachnoid in origin, conferring a threefold to fourfold increased risk for moderate and heavy drinkers compared with nondrinkers.