Enterococci are common causative agents in a broad range of human infections. Although formerly considered to be of low virulence, in recent years they have emerged as important pathogens, particularly in the hospital environment. Enterococci are not only intrinsically resistant to several antibiotics, but are also characterised by a potent and unique ability to exchange genetic material. With the increasing prevalence of strains resistant to ampicillin, aminoglycosides and glycopeptides, serious therapeutic difficulties have become more common. Epidemiological aspects, the mechanisms of action, the detection of antibiotic resistance, and the situation of enterococci in Sweden are discussed in the article.