This is a prospective, descriptive and analytic study conducted from July 2011 to September 2011 at the Children National Hospital Albert Royer of Dakar and at the Vélingara Health District. It was focused on children under 15 without reference to HIV status. For each child, a sample of stool was examined by the Ziehl-Neelsen modified staining and by ELISA using the "Cryptosporidium Antigen Detection Microwell ELISA kit" designed to detect Cryptosporidium spp antigens. The aim of our study was to determine the prevalence of cryptosporidiosis in rural and hospital areas and to measure the performance of the ELISA kit that we used. Out of the 375 stool examinations performed with the Ziehl-Neelsen modified staining, 17 had revealed the presence of Cryptosporidium spp (4.53%). The prevalence in rural areas was 2% while the hospital prevalence was 7.4%, of which 1.8% (1/57) were from urban areas and 9.8% (12/122) from suburban areas. No positive case was observed in children over 10 years. By ELISA, 23 positives cases were reported corresponding to a prevalence of 6.13% (1.8% in children living in urban areas, 13.1% in children from suburban areas and 3%living in rural areas).The correlation of this assay with the Ziehl-Neelsen modified staining, considered as the reference method, found that this assay had a sensitivity of 58.82% and a high specificity reaching 96.37%. The positive predictive value (PPV) was 43.4% while the negative predictive value was 98%. Cryptosporidiosis is a significant cause of parasitic infection among children in Senegal. Antigen detection of Cryptosporidium spp by ELISA in stool can be a complementary tool in the diagnosis of cryptosporidiosis.