Cryptosporidium parvum is a protozoan which causes self-limiting diarrhea in immunocompetent subjects, and severe life-threatening disease in immunocompromised patients. Cryptosporidiosis is more common in developing countries and in infants. In this paper we have evaluated the prevalence of C. parvum in 368 hospitalized children with enteritis, of whom 359 were immunocompetent and 9 HIV-infected. Stool specimens were concentrated by sedimentation and stained with a modified Ziehl-Neelsen method. Cryptosporidium parvum oocysts were found in 7 (1.90%) out of 368 subjects. Six of these were immunocompetent (with an infection rate in this population of 1.67%) and 1 HIV-infected, asymptomatic except for diarrhea. In all children symptoms of enteritis and oocyst excretion cleared within 10 days. These results indicate that the prevalence of C. parvum as a causative agent of diarrheal illness in hospitalized immunocompetent children is rather low in our region (Apulia, South Italy).