Enterococcus species are common in nosocomial bloodstream infections and their incidence is rising. Although well recognized in several serious bacterial infections, the influence of appropriate antimicrobial therapy in enterococcal bacteraemia has not been fully settled. The aim of the study was to determine whether administration of inappropriate antibiotics in enterococcal bacteraemia is an independent risk factor for mortality, among other known and suspected risk factors. We conducted a cohort study of E. faecalis/faecium bacteraemia during a 3-year period at a single tertiary care hospital in Denmark. Patients with growth of non-enterococcus co-pathogens apart from the enterococcal bacteraemia were also included, as were patients with repeated enterococcal bacteraemia. Time to appropriate antimicrobial therapy was counted from the first episode. Appropriate antibiotic therapy was defined as any therapy with documented clinical effect, in vitro activity and a minimum treatment length of 6 days. Multivariate regression models were built to determine the independent risk factors for mortality. We included 196 patients with enterococcal bacteraemia. Appropriate antibiotics for at least 6 days were administered in 146 of these (74%). Thirty-day mortality was 26%. Multivariate logistic regression identified independent predictors of 30-day all-cause mortality: appropriate antimicrobial therapy for >/=6 days (odds ratio for mortality 0.33, 0.14-0.79), ICU admission (4.2, 1.7-10), thrombocytopenia (3.9, 1.6-9.3), chronic liver failure (3.3, 1.1-10) and age >/=60 years (2.2, 0.99-5.0). Antibiotics not appropriately covering enterococci are frequently administered empirically in suspected bloodstream infections. Inappropriate antibiotic therapy was an independent risk factor for mortality in enterococcal bacteraemia