The isolation ratio of coagulase negative staphylococci (CNS) from urinary tract infections have increased remarkably recently, but the exact identifications CNS, which are classified into 17 species, have not been well examined in clinical laboratories. We isolated and identified the species of CNS from patients with urinary tract infections and compared this with the pattern of species isolated from urethral openings (UO) of non-infected females. The incidence of CNS infection in complicated urinary tract infection (C-UTI) was 9.4% (41/438). Only CNS was isolated in 21 out of 41 cases (58.8%). These data suggest that CNS may be causative pathogens of urinary tract infection. The isolated CNS comprined S. epidermidis (51.4%), S. haemolyticus (24.5%) and some others (a few percent each) in cases of C-UTI. On the other hand, in UO from the non-infected control group, S. epidermidis and S. haemolyticus predominated. The incidence of the CNS species in C-UTI and UO of noninfected females was similar, and CNS which reside in the UO may ralate to the pathogens in C-UTI.