Three known alcoholics without medical complications were given alcohol ad lib. Platelets were counted periodically during and following the period of drinking. There was an initial transient decline in platelet levels. A more gradual decline then occurred after the second day. Upon cessation of drinking there was a slow recovery of platelet values. None of the subjects showed evidence of liver disease, folate deficiency, or intravascular coagulation. The results suggest that alcohol has a direct effect on platelet turnover.