The purpose of this study was to establish the prevalence of Cryptosporidium parvum among infants of less than 5 years of age, resident in the urban area of Campo Grande, Mato Grosso do Sul State, Brazil, 1996/97, through parasitological examinations and epidemiological analysis of the diagnosed cases. It was a transverse study with domiciliary inquiry and we evaluated 1051 fecal samples processed by the Blagg method, and a modified Ziehl-Neelsen staining was used for research of oocysts of C. parvum. We can concluded that the prevalence of C. parvum (1.1%) was not statistically significant; 58.3% of the children with positive diagnosis presented diarrhea, suggesting an association between this sign and the presence of the parasites; C. parvum was more frequent among children aged between 25 to 36 months (50%), but this was not statistically significant; sex did not have a differential role in relation to the cryptosporidiosis; out of the 12 children with cryptosporidiosis, 10 had contact with domestic animals (dogs and or cats).