The postservice mortality (through December 1983) of a cohort of 9324 US Army veterans who served in Vietnam was compared with that of 8989 Vietnam-era Army veterans who served in Korea, Germany, or the United States. Over the entire follow-up period, total mortality in Vietnam veterans was 17% higher than for other veterans. The excess mortality occurred mainly in the first five years after discharge from active duty (rate ratio, 1.45; 95% confidence interval, 1.08 to 1.96) and involved motor vehicle accidents, suicide, homicide, and accidental poisonings. Thereafter, mortality among Vietnam veterans was similar to that of other Vietnam-era veterans, except for drug-related deaths, which continued to be elevated. An unexpected finding was a deficit in deaths from diseases of the circulatory system among Vietnam veterans. The excess in postservice mortality due to external causes among Vietnam veterans is similar to that found among men returning from combat areas after World War II and the Korean War.