We report a prospective study of the cases of acute diarrhea admitted to our pediatric service during one year (n = 172) to elaborate a screening method to identify patients with bacterial diarrhea. A bacterial causative organism was identified in 31.4%. The most common species was Salmonella, followed by Campylobacter. We evaluated the clinical presentation parameters, looking for differences between the group were a bacterial organism was isolated and in the group where it was not. We designated a score valid as a first level screening for bacterial diarrhea. With a score greater than or equal to 7 the sensitivity was 81.5% and the specificity 60.2%. The latter increased to 95% when occult blood in feces was associated with the greater than or equal to 7 score (second screening level). We propose this clinical score as a criterion for the indication of fecal cultures in children with acute gastroenteritis.