Diarrheal diseases with diarrhea are the most frequent cause of morbidity and mortality in children; however the causative agent cannot be identified always, which suggests the presence of unknown enteropathogens inducing diarrhea. The isolation of Acinetobacter sp. from feces of children with acute diarrhea, unrelated to known enteropathogens motivated this investigation to detect a possible enterotoxigenic effect on HT-29 cells. The study population comprised 150 children with an age range from 0 to 5 years old; 120 were assisted in the "Hospital Materno Infantil del Este'' with gastrointestinal syndrome and 30 healthy controls who went to the center for routine analysis. In 25% of symptomatic patients were diagnosed parasites and bacteria, identified routinely. From four symptomatic patients were isolated three Acinetobacter baumannii strains and two A. calcoaceticus strains. The strains were cultured in brain-heart infusion for 24 and 48 hrs, at 35 degrees C, and the supernatants were obtained by centrifugation and filtration and their activity tested on HT-29 cell monolayers. The supernatants of the three strains of A. baumannii induced alterations of the cell monolayer, showed by detachments of cell monolayers, cell segregation, cell rounding and swelling. These effects were more intense with the 48 h culture exoproducts of the 016 strain, which were higher than the positive control. This toxigenic effect of A. baumannii, could represent a pathogenic mechanism whose definition requires more studies to determine the possible role in the pathogenicity of this bacillus.