To evaluate cross infection and a possible outbreak of Enterococcus faecalis urinary tract infection (UTI) in our urology ward, we studied the DNA fingerprinting of E. faecalis strains isolated from nosocomial UTI patients, in the period 1982-1996, using arbitrarily primed polymerase chain reaction (AP-PCR) analysis. The serovar and amplified products of DNA extracted from clinically isolated urinary E. faecalis strains by the AP-PCR method were analyzed, and the respective isolation periods of E. faecalis-positive UTI patients were investigated. There were nine patients with E. faecalis UTI between March and May 1994 and all strains isolated from their urine specimens were serovar type 7. AP-PCR revealed that five of the nine isolates had the same pattern. It appeared that these strains had caused the outbreak of E. faecalis UTI. Cross-infection between patients with E. faecalis UTI was demonstrated by genomic fingerprinting, suggesting that cross infection had occurred via urinary catheters or by hand contact in our ward. We may, therefore, reasonably conclude that we should beware of the transmission of urinary E. faecalis and take countermeasures against its dissemination.