The incidence of epilepsy occurring more than one month after injury has been studied in 422 veterans who sustained head injuries during or immediately after the Korean campaign. The selection of cases, methods of follow-up, and the criteria used for the diagnosis of epilepsy are described. Epilepsy followed 32% of missile wounds, 8 per cent of non-missle wounds, and one of the injuries by blast. The incidence of epilepsy after missile wounds in which the brain was penetrated was 42%, after depressed fractures from all causes 22%, after other missile injuries 12%, and after other non-missile injuries 6%. A family history of epilepsy was more frequently obtained in the epileptic group, suggesting that an inherited predisposition may contribute to the appearance of post-traumatic seizures. The incidence of epilepsy was positively correlated with complications of the wound such as infection or hematoma, the duration of unconsciousness or post-traumatic amnesia, and the presence of focal neurological signs. Retained metallic fragments were unrelated to the development of epilepsy. Generalized seizures were more common than focal seizures after non-missile injuries; the types of seizure are described. Factors which appeared to precipitate seizures in members of this series in- clude excessive alcohol consumption, watching television, sleep, and emotional stress. The course of post-traumatic epilepsy over seven to ten years shows a strong tendency to natural remission. The results are discussed in the light of previous reports.