The cause of death (besides dehydration) for 140 diarrhoeal patients who died in hospital following rehydration was determined by autopsy examination. Children under 5 years comprised 74% of the patients. Diarrhoeal pathogens were identified as Shigella spp. in 27%, enterotoxigenic Escherichia coli in 17%, Entamoeba histolytica in 16%, Campylobacter jejuni in 12%, Salmonella spp. in 4%, Vibrio cholerae in 4%, and Giardia lambliain 4% of cases. The most frequent underlying causes of death were colitis in 44% and pneumonia in 38%. The most frequent immediate causes of death were septicaemia in 27%, hypoglycaemia in 9%, and hypokalaemia in 9%; multiple causes of death were present in 89% of cases. Kwashiorkor or marasmus was present in 59% and fatty degeneration of the liver was detected in 61% of cases. It is concluded that, in susceptible children, diarrhoeal pathogens produce destructive inflammation in the intestine and cause death or contribute to it by provoking disease in other tissues, especially septicaemia and fatty liver, or by combining these effects with antecedent or concomitant conditions, especially pneumonia and malnutrition.