A study was conducted examining leading causes of death among military personnel on active duty between 1980 and 1993. Data obtained from the Report of Casualty (DD Form 1300) of the Department of Defense's Worldwide Casualty System were reviewed, and causes of death were categorized as unintentional injury, natural causes, homicide, suicide, hostile action, and other. There were 26,101 deaths of military personnel identified for an annual rate of 92 per 100,000. More than 95% of these deaths occurred in males, 78% in whites, 87% in enlisted personnel, and 81% in those 34 years of age or younger. The leading cause of death in both males and females was unintentional injuries followed by natural causes. Among males, suicide was the third leading major cause of death followed by homicide, whereas among women deaths from homicide exceeded those from suicide. Combat was the cause of about 2% of all deaths. The highest rate of death due to unintentional injury was seen in the Marine Corps and the lowest was in the Air Force. An inverse relationship was seen between the rate of unintentional injury death and age. The Marine Corps had the lowest rate of deaths due to natural causes; the death rate in this category increased 4.5 fold in those over 35 years of age. Males and blacks had the highest death rates from natural causes. The rate of suicide was similar between males and females and highest in the Marine Corps. The homicide rate was also the highest in the Marine Corps and among women. Young adults and blacks were found to be at the greatest risk of homicide. The authors conclude that this information may be useful in the development of appropriate prevention strategies.