We conducted a study on 81 clinical isolates of enterococci (65 Enterococcus faecalis and 16 Enterococcus faecium) collected consecutively over a one year period at our University Hospital. Of them, 10 (15%) Enterococcus faecalis and 6 (38%) Enterococcus faecium showed high level resistance to aminoglycosides, were all acquired in surgical units and in five cases they were responsible for invasive infections. Ampicillin and imipenem were active only against Enterococcus faecalis. Vancomycin and teicoplanin were bacteriostatic; however, teicoplanin MICs were lower and in 45% of cases its MBC values were within clinically achievable serum concentrations. Ciprofloxacin and cotrimoxazole were active in vitro.