Studies in men suggest that light-to-moderate alcohol intake is associated with a reduction in overall mortality, due primarily to a reduced risk of coronary heart disease. Among women with similar levels of alcohol consumption, an increased risk of breast cancer has been noted that complicates the balance of risks and benefits. We conducted a prospective study among 85,709 women, 34 to 59 years of age and without a history of myocardial infarction, angina, stroke, or cancer, who completed a dietary questionnaire in 1980. During the 12-year follow-up period, 2658 deaths were documented. The relative risks of death in drinkers as compared with nondrinkers were 0.83 (95 percent confidence interval, 0.74 to 0.93) for women who consumed 1.5 to 4.9 g of alcohol per day (one to three drinks per week), 0.88 (95 percent confidence interval, 0.80 to 0.98) for those who consumed 5.0 to 29.9 g per day, and 1.19 (95 percent confidence interval, 1.02 to 1.38) for those who consumed 30 g or more per day, after adjustment for other predictors of mortality. Light-to-moderate drinking (1.5 to 29.9 g per day) was associated with a decreased risk of death from cardiovascular disease; heavier drinking was associated with an increased risk of death from other causes, particularly breast cancer and cirrhosis. The benefit associated with light-to-moderate drinking was most apparent among women with risk factors for coronary heart disease and those 50 years of age or older. Among women, light-to-moderate alcohol consumption is associated with a reduced mortality rate, but this apparent survival benefit appears largely confined to women at greater risk for coronary heart disease.