343 children with acute diarrhea were studied from january 1976 to september 1977. Rotavirus was the agent most frequently isolated (18 per cent) followed by Shigella (12 per cent) and Salmonella (10 per cent). Enterotoxigenic E. coli was identified in 8 per cent and invasive E. coli only in two cases. 80 per cent of isolated rotavirus fell in the neonate group and 25 per cent in the infant group. Diarrhea caused by rotavirus had a short duration, fever was negligible and abundant liquid stools were present without leukocytes in the fecal mucus and with a high percentage (48 per cent) of transient lactose intolerance. Polymorphonuclear leukocytes were found in fecal mucus in 75 per cent of cases caused by Shigella and only in 40 per cent of cases where the causal agent was Salmonella.