Alcohol consumption has both adverse and beneficial effects on survival. We examined the balance of these in a large prospective study of mortality among U.S. adults. Of 490,000 men and women (mean age, 56 years; range, 30 to 104) who reported their alcohol and tobacco use in 1982, 46,000 died during nine years of follow-up. We compared cause-specific and rates of death from all causes across categories of base-line alcohol consumption, adjusting for other risk factors, and related drinking and smoking habits to the cumulative probability of dying between the ages of 35 and 69 years. Causes of death associated with drinking were cirrhosis and alcoholism; cancers of the mouth, esophagus, pharynx, larynx, and liver combined; breast cancer in women; and injuries and other external causes in men. The mortality from breast cancer was 30 percent higher among women reporting at least one drink daily than among nondrinkers (relative risk, 1.3; 95 percent confidence interval, 1.1 to 1.6). The rates of death from all cardiovascular diseases were 30 to 40 percent lower among men (relative risk, 0.7; 95 percent confidence interval, 0.7 to 0.8) and women (relative risk, 0.6; 95 percent confidence interval, 0.6 to 0.7) reporting at least one drink daily than among nondrinkers, with little relation to the level of consumption. The overall death rates were lowest among men and women reporting about one drink daily. Mortality from all causes increased with heavier drinking, particularly among adults under age 60 with lower risk of cardiovascular disease. Alcohol consumption was associated with a small reduction in the overall risk of death in middle age (ages 35 to 69), whereas smoking approximately doubled this risk. In this middle-aged and elderly population, moderate alcohol consumption slightly reduced overall mortality. The benefit depended in part on age and background cardiovascular risk and was far smaller than the large increase in risk produced by tobacco.