At the end of 1999, a case of polymicrobial ventriculitis in the Department of Neurosurgery followed by an outbreak of Serratia marcescens mediastinitis in the intensive care unit of cardiovascular surgery occurred. These nosocomial surgical infections were considered to be the result of contamination of surgical sites with inadequately sterilized instruments or theatre linen. An epidemiological survey was focused on the central sterilization unit of the hospital. The microbiological results of this survey proved that the cause of the Outbreak was the use of inadequately decontaminated theatre linen. This study indicates that strict infection control measures including the control of sterilization procedures and a well-organized infection control team are necessary to prevent nosocomial surgical infections. (C) 2002 The Hospital Infection Society.