Enterococci have emerged as important nosocomial pathogens with increasing antimicrobial resistance. Within the past 5 years, vancomycin-resistant strains have disseminated throughout the United States and Europe. Many of these organisms are also highly resistant to beta-lactams and aminoglycosides, making them virtually untreatable. Because optimal therapy for these infections is unknown, attributable mortality rates for patients with vancomycin-resistant enterococcal bacteremia are extremely high. Recently identified risk factors for acquisition include prolonged hospitalization, prior antibiotic use, and serious underlying illness. Until effective therapy is available, prevention of infection by proper infection control procedures and judicious antibiotic use is critical.