In recent decades, Serratia marcescens has been established as a cause of infections difficult to treat, and several outbreaks of nosocomial infections have been reported, mostly from the USA. However, serratia infections affecting bones and joints are very rare; only a few such cases have previously been reported from Europe. We report 7 patients with orthopaedic infections by S. marcescens chiefly of nosocomial origin where previous antibiotic therapy apparently was a predisposing factor. The clinical course was generally protracted, often requiring repeated surgical interventions. Also, in some cases adequate therapy was considerably delayed as serratia was considered to be a nonpathogenic saprophyte. Multiresistance to antibiotics was a major clinical problem. However, the third generation cephalosporins are often effective against serratia and the aminoglycosides can thus be avoided. The increased use of prophylactic antibiotic therapy in orthopaedic surgery may bring about an increase in the incidence of infections by multiresistant microorganisms in orthopaedic wards.