One hundred consecutive patients (67 men, 33 women) aged from 15–55 with acute ischemic brain infarction verified by computed tomography and/or angiography and/or brain scanning were studied. In 40 cases the onset of symptoms was preceded within 24 hours by ethanol intoxication. Ethanol intoxication preceding brain infarction was 4–7 times as common in men and 6–15 times as common in women as ethanol intoxication in the general Finnish population of the same age and sex. Nineteen of the patients were heavy drinkers. Heavy drinking was twice as common in men and 5 times as common in women as heavy drinking in the general Finnish population of the same age and sex. Both occasional ethanol intoxication and regular heavy drinking seem to carry an increased risk of ischemic brain infarction. The ethanol-induced risk was highest in middle-aged women and young men.