A severe illness characterised by bloody diarrhoea and intestinal dysfunction was recognised at an evacuation site on the Thai-Kampuchean border. From June, 1985, to July, 1986, the illness occurred in 62 Khmer children aged 10 months to 10 years (mean 4 years); it was characterised by bloody diarrhoea (94%), fever (90%), and abdominal pain (78%). The overall mortality rate was 58%. Among 16 children who died and underwent necropsy, small-intestinal necrosis of varying severity was found; in 5 of these children small-intestinal lesions with areas of full-thickness necrosis were seen that histologically resembled those in cases of enteritis necroticans (pigbel) in Papua New Guinea. Beta-toxin-producing Clostridium perfringens type C was isolated from 2 of 23 children from whom specimens for anaerobic cultures were collected, and antibodies to beta toxin were detected in 5 of 9 survivors but not in 10 healthy, age-matched control children. These cases show that enteritis necroticans can cause substantial morbidity and mortality outside Papua New Guinea.