The present study, conducted from March 1998 to July 2000, determined the etiology of acute diarrhea in 253 young children and infants from Cartagena and Sincelejo, Colombia. In 253 stool samples, the following enteric pathogens were recovered: rotavirus type A (36.6%) as the major agent, Salmonella spp (9.0%), Shigella spp (8.0%), enteric pathogenic Escherichia coli (6.0%), enteric hemorragic Esc. coli (2.8%), Providencia alcalifaciens (2.8%), Aeromonas hydrophila (2.0%), Yersinia enterocolitica (0.8%), Entamoeba hystolitica (10%), Giardia lamblia (4%), Endolimax nana (3.2%), Ascaris lumbricoides (2.8%), Ent. coli (1.2%), Balantidium coli (0.8%), Blastocystis hominis (0.8%), Dypilidium caninum (0.4%) and hook worm sp. (0.4%). Infection with more than one pathogen occurred in 96 (37.9%) patients. Rotavirus and enteric pathogenic Esc. coli were frequent. Concurrent infection by more than one parasite occurred in 18.6% of the infants. Most rotavirus infections (76.7%) occurred in infants under 12 months. Vomiting, severe dehydration and fever were frequent in children with rotavirus infection. At least one fecal marker of inflammatory diarrhea was registered in patients with bacterial infection. To our knowledge, this is first report of P. alcalifaciens associated with infantile diarrhea in Colombia and the first description of Esc. coli O157:H7 and Y. enterocolitica in our region.