The postservice mortality of a cohort of 10,716 US Marine veterans who served in Vietnam was compared with that of 9,346 Marine veterans who did not serve in Vietnam. There was a significant excess of death for Vietnam Marines from all causes and all external causes. After adjustments for age and rank in military, overall mortality continued to be statistically significant, with a relative risk of 1.15 (95% confidence interval (CI) = 1.02 to 1.29) for Vietnam Marines compared to non-Vietnam Marines. All external causes was also significant, with a relative risk of 1.21 (95% CI = 1.00 to 1.47). The excess overall mortality was mainly due to excess deaths from external causes. The risks for several site-specific cancers were elevated but not statistically significant. Periodic follow-up of this Marine cohort should continue to determine whether there are statistically significant differences in the mortality patterns of Marine Vietnam and non-Vietnam veterans, especially for cancers.