We determined the incidence of enterovirulent E. coli (EVEC; which can to cause gastrointestinal infections) in strains isolated from patients with both of the major inflammatory bowel diseases (IBD), Crohn's disease (CD) and ulcerative colitis (UC) and from patients with noninflammatory bowel diseases (nonIBD). Cell detachment E. coli (CDEC) were detected in 14 % of all strains. A significant difference in the presence of CDEC was found between the groups of strains isolated from UC (24.1 %), nonIBD (11.9 %) and CD (4.7 %). Enteroaggregative E. coli (EAggEC) were detected in 2.5 %, typical enteropathogenic strains (EPEC) in 1.3 % and enterotoxigenic ones (ETEC) in 1.5 %. Enteroinvasive (EIEC) and shigatoxin producing E. coli (STEC) were not detected. Some strains showed a high invasion level in gentamicin-protection assay. These strains could therefore belong to adherent-invasive E. coli (AIEC) because they are free of genes encoding invasins (ipaH, ial) and are equipped with fimA gene. However, complete characterization of these strains and their classification as AIEC will require further tests.