Enteroaggregative (EAEC) and atypical enteropathogenic (EPEC) Escherichia coli are important bacterial etiologic agents causing diarrhea among children. The aim of the present study was to examine the impact of virulence factors predisposes to diarrhea. In this study some virulence properties were examined on 11 EAEC and 8 EPEC strains identified by Polymerase Chain Reaction (PCR), isolated from stool samples of children were analyzed genotypically and phenoltypically for the prevalence of virulence factors. The most frequently detected factor was resistance to serum (94%), followed by curli fimbriae (78%), biofilm production (73%), and gene coding for Extended-Spectrum Beta-Lactamase (ESBL) (68%). EPEC isolates showed at least three of the evaluated properties, while EAEC isolates showed at least two. The prevalence of these virulence factors between the two strains showed no statistical difference. This study showed the heterogeneity of the virulence profile of the isolates of EAEC and atypical EPEC strains and suggests that this diversity may influence in the disease severity.