Cryptosporidium spp. is the most important diarrhea-causing parasitic protozoa in children and has been recognized as the predominant cause of waterborne and foodborne outbreaks. Direct transmission person-to-person or animal-to-person is also possible. In France, little epidemiological and molecular information is available regarding the current status of Cryptosporidium spp. infections in children. Most laboratories do not test for Cryptosporidium in stool specimens submitted for routine parasitological examination and cryptosporidiosis remains underdiagnosed. OBJECTIVES : This study was devoted to determine the prevalence (and the genetic diversity of Cryptosporidium) of Cryptosporidium infection in immunocompetent children with diarrhea. METHODS : Stool samples from children under 16 years of age were collected between January 2007 and october 2014, admitted to the Department of Pediatrics of Rouen University Hospital or who consulted their GP in the area of St Valéry en Caux (Seine-Maritime). All samples were screened for the presence of Cryptosporidium oocysts using Heine staining and genotype determination of Cryptosporidium isolates was based on PCR targeting the Hsp70 and the 18S rRNA genes followed by 18S rRNA sequencing. RESULTS :Out of a total of 7443 diarrheic faecal samples, the microscopic examination showed that 64 samples were positive for presence of Cryptosporidium and overall prevalence of Cryptosporidium infection was 0,8 % (ranging from 0,4 % in 2011 to 1,6 % in 2013). The mean age of children with Cryptosporidium infection was 5 years, median age was 3 years and 4 months (ranging from 6 months to 16 years). None of the children positive for the parasite exhibited signs of immunodeficiency or had received immunosuppressive drugs. Most if not all cases had loose stools, over 75% of children had vomiting. Hospitalization was necessary for 42patients, due to dehydration in most cases. 80 % of cases occurred between July and November and 50 % in August and September. Genotyping (18S rRNA) revealed 45 and 17 infections by C. parvum and C. hominis, respectively. Twelve children had travelled abroad (9 infected with C. hominis et 3 with C. parvum). Subgenotype analysis of isolates at the 60-kDa glycoprotein (GP60) locus identified mainly subtype IIaA15G2R1 for C. parvum. CONCLUSIONS : The current study shows that Cryptosporidium is one of the aetiological agents responsible for childhood watery diarrhoea in Upper-Normandy, thus stressing the importance of routine stool examination for Cryptosporidium oocysts. The fact that the species C. parvum, mainly subtype IIaA15G2R1, was detected in most of locally infected children suggests that cryptosporidiosis must primarily be considered as a zoonotic disease in Upper-Normandy region. This work constitutes the first study outlining cryptosporidiosis prevalence in children in France. These data should be confirmed in future studies with larger children populations from other French geographical regions.