A prospective cohort study of a random sample of 1,000 Australian Army Vietnam veterans analyzed risk factors for postwar mortality using information from Army records and personal interview assessments of physical and mental health measured approximately 15 years earlier. This enabled examination of the role of combat, military service, and psychiatric status including post-traumatic stress disorder (PTSD) on postwar civilian mortality. Factors predicting mortality were identified using multivariate statistical methods including logistic and Cox regression. Mortality was associated principally with age, enlistment route (regular vs. national service conscripts), and conduct while in service in the whole cohort. Additional analysis using interview data revealed that mortality was predicted by age, smoking status, chronic diabetes, bronchitis and blood diseases, and treatment for cancer and heart disease. Psychiatric status including PTSD diagnosis was not associated with mortality. Veterans' mortality risk may be reduced by attention to smoking and alcohol both in-service and postservice.