Fifty-nine enterococci isolated from 18 patients in an intensive care unit (ICU) and 21 patients in general wards (GW) at Royal Perth Hospital (RPH) during a period of 14 months were examined for antibiotic resistance by susceptibility testing and DNA polymorphism by pulsed-field gel electrophoresis. The study showed that penicillin-resistant Enterococcus faecium is a common nosocomial isolate in ICU. The DNA patterns of various strains of E. faecium and E. faecalis were closely related in most consecutive isolates from the same patients but were generally different for isolates from different patients. Thirty two different DNA patterns were identified for 59 isolates from 39 patients. Identical or similar DNA patterns were also identified for some isolates from different patients, suggesting that cross-infection had occurred between patients in ICU and GW. These data suggest that cross-infection occurred more commonly in ICU than in GW and are consistent with the known higher risk of ICU patients for nosocomial infection.