Abstract.A cross-sectional study was conducted for assessing the prevalence of and risk factors associated with Cryptosporidium parvum in diarrheic children who were hospitalized in Goiânia, capital of Goiás State in Brazil. A crude prevalence of 14.4% (64 of 445) was observed using a direct immunfluorescent assay (DFA), but the true prevalence was 18.7% (83 of 445) when a gold standard of immunomagnetic separation was used in combination with the DFA. Infection was more predominant in children less than 24 months old (odds ratio [OR] ס 0.50, 90% confidence interval [CI] ס 0.36-0.68, P ס 0.0001), and males were 2.2 times more at risk for infection when compared with females (OR ס 2.2, 90% CI ס 0.13-3.8, P ס 0.01). The socioeconomic, intra-familial, and environmental factors associated with cryptosporidiosis were day care attendance, household children with diarrhea up to 30 days prior to the interview, contact with surface water within past 30 days prior to the interview, dwelling distance from a body of water, and the late rainy season (P < 0.10). C. parvum was not associated with the parent's occupation, household sleeping arrangements, number of caregivers, breast-fed children, diet and type of food hygiene, source and type of treatment of drinking water, presence of sewage, and animal exposure (P > 0.10). Although weight was not found to be associated with infection, children infected with C. parvum weighed on average 2.0% less than children not infected with C. parvum (P > 0.10). Thus, C. parvum is an important etiologic agent of childhood diarrhea and should be identified in routine parasitologic tests of diarrheal stool samples.