The activity of a new oxazolidinone antimicrobial, AZD2563, was assessed against >500 clinical isolates of enterococci representing six species. All isolates, including those resistant to other antibiotic classes, were inhibited by AZD2563 at concentrations </=2 micro g/ml, except for four strains resistant to linezolid. In most cases, AZD2563 was twofold more active than linezolid against enterococci.