Isolates of Escherichia coli from 31 Norwegian and 31 Russian females with significant bacteruria who presented with clinical signs of urinary tract infection (UTI) were tested for antimicrobial sensitivity, the presence of virulence genes, phylogroup distribution and clonal affinity. Twenty isolates, representing the full clonal diversity of a collection of 138 intestinal isolates of E. coli from healthy Norwegian females, served as a reference group. Russian UTI isolates belonged more often to phylogroup A and possessed fewer virulence genes than did Norwegian isolates. UTI isolates of E. coli were genetically heterogeneous and had a high degree of antimicrobial sensitivity.