In order to explore the incidence of Clostridium difficile-associated diarrhea(CDAD)  among children of diarrhea and to give a retrospective clinical analysis of this kind of diarrhea, we employed an ELISA-based assay of Clostridium difficile toxin A to the stool samples of children with diarrhea from February 2007 to September 2007 in Children’s Hospital of Fudan University. Anaerobic bacteria culture was also performed for each recruited sample. Four cultured Clostridium difficile strains were isolated and subjected to a Multi-Locus VNTR Assay(MLVA) to investigate the epidemiological information. 111 cases were recruited, among which none cases were positive for both toxin A investigation and anaerobic bacteria culturing, 16 cases were toxin A positive while culture negative, 4 cases were toxin A negative while culture positive, and 91 cases were either toxin A positive nor culture positive. The comparison of the incidence of CDAD of different courses between hospital-acquired and community-acquired infection has shown no statistically significant differences(P>0.05). The four cultured Clostridium difficile isolates were found to related to each other to some extent in the phylogenetic tree. In conclusion, the Clostridium difficile infection in Shanghai is sporadic, but may related phylogeneticly to some extent. The clinical manifestation of CDAD is of no specialty than those without evidence of CD infections.