The authors compare the mortality experience of a national sample of diabetic men and women with their nondiabetic counterparts. The study population consists of respondents from the First National Health and Nutrition Examination Survey (NHANES I), conducted in 1971-1975, who were traced in 1982-1984 through the NHANES I Epidemiologic Follow-up Study. Over the nine-year follow-up period, the age-adjusted death rates for diabetic men and women were twice the rates for nondiabetics. About 75% of the excess mortality among diabetic men and 57% among diabetic women was attributable to cardiovascular disease deaths. After adjustment for age, systolic blood pressure, serum cholesterol, body mass index, and smoking, the relative risk of death was 2.3 for diabetic men and 2.0 for diabetic women. The relative risk for diabetics was highest for ischemic heart disease mortality (2.8 for men and 2.5 for women) and lowest for noncardiovascular disease deaths (1.4 for men and 1.1 for women). When subjects who reported having had a heart attack prior to the baseline examination were excluded, the relative risks for ischemic heart disease mortality among diabetics remained substantial (2.4 for men and 2.6 for women). There was little evidence that the relative risk of death for diabetics compared with nondiabetics differed by age or sex, although 95% confidence intervals around these estimates were wide.