Between April 1, 1999 and June 30, 2000, 144 isolates of enterococci (one per patient) from cultures of several anatomic sites were collected. One hundred and nineteen (82.6%) E. faecalis, 11 (7.6%) E. faecium and 14 (9.7%) of other species (5 E. raffinosus, 4 E. avium, 3 E. casseliflavus, 1 E. pseudoavium, and 1 E. dispar) were associated with clinical infections. The most common sites of isolation were: the urinary tract 54.9%, abdominal cavity 12.5%, surgical wounds 12.5%, abscesses 6.9% and diabetic foot 6.2%. High-level resistance to gentamicin or streptomycin or both was detected in 48.6% of the isolates. E. faecium and E. raffinosus were significantly more resistant than E. faecalis to ampicilin and imipenem. None of the strains exhibited beta-lactamase activity. One strain of E. faecium (0.7%) was resistant to vancomicin and teicoplanin (Van A phenotype) and two strains of E. casseliflavus (1.4%) showed low level of resistance to vancomicin (Van C phenotype). Because of these diverse antimicrobial resistance mechanisms, successful treatment and control of enterococcal infections with current antimicrobial agents are becoming increasingly difficult.