An outbreak of acute diarrhea (A.D.) caused by serogroup 0142 Enteropathogenic E. coli (0142 EPEC) among neonates from the wards of a general hospital is described on clinical and epidemiological grounds. Seventy patients were affected from January through September 1982, all of them had negative stool cultures for Salmonella and Shigella sepecies. Fourteen of twenty two neonates specifically investigated for E. coli rendered positive isolations, in all cases 0142 EPEC. In this otubreak 92,8% of patients were preterm and 85,7% of the whole group suffered severe symptoms, with dehydration and metabolic acidosis. Mortality rate was 2,9°^ The relationships between EPEC infection and the relatively inmunodeficient host represented by the newborn are discussed. Breat feeding reduced the incidence and severity of diarrhea and the complications of infection.