At St Elizabeth Hospital Medical Center in Youngstown, Ohio, USA, the first blood culture isolate of Enterococcus faecalis with high-level gentamicin resistance (MIC > 2000 mg/L) was seen in 1985, and the prevalence of high-level gentamicin resistance among enterococci isolated from blood cultures during 1985-8 was 9%. During the period 1989-91, the prevalence of high-level gentamicin resistance among enterococci isolated from blood cultures increased to 35% (44 of 126 strains). Increases in the prevalence of high-level resistance to amikacin, tobramycin, netilmicin, kanamycin and streptomycin were also demonstrated. Ten of 44 strains (23%) with high-level gentamicin resistance did not exhibit high-level resistance to streptomycin. Of the 126 strains of enterococci, 52% had high-level resistance to at least one aminoglycoside.