During the years 1974-86 in the Israel Defense Force (IDF), 83 soldiers aged 17-39 years died suddenly and unexpectedly. Cardiac causes accounted for 56% of the deaths, neurological causes for 19%, other diseases for 8% and in 17% the cause of death was unknown. Causes of death varied between soldiers younger and those older than 30 years of age. Ischemic heart disease accounted for 58% of deaths in soldiers greater than 30 years old but was an infrequent cause of death in subjects less than 30 years (4%). Congenital cardiac anomalies (27%) and myocarditis (15%) accounted for most deaths in subjects less than 30 years of age. Epilepsy was a common cause of sudden death (10%), occurring mainly during sleep, and was related to poor medical control. Effort-related deaths occurred in 25 cases (30%) and were mainly associated with cardiac causes. Syncope (18%) and chest pain (18%) were common symptoms prior to death. According to our data and previous reports, sudden death continues to be an unresolved medical problem in young adults. Preventive measures should include a more thorough evaluation of symptoms such as syncope and chest pain, particularly when occurring during or after exercise. Furthermore, early coronary artery disease should not be disregarded in subjects as young as 30 years of age.