We identified 29 episodes of suppurative thrombophlebitis in 27 patients admitted to a large general hospital between May 1980 and May 1984. In 25 patients, the intravenous cannulae had been in place for more than 3 days. Streptococcus faecalis, Pseudomonas aeruginosa or one of the Enterobacteriaceae were implicated in 14 patients. All these patients had recently undergone abdominal surgery or had a major intraabdominal inflammatory process at the time they developed thrombophlebitis. The remaining 13 patients were infected with Staphylococcus aureus, other grampositive cocci or Candida species. Only two of these had an active abdominal process at the time of their infection (x2 = 16.08, P<0.001). There is an apparent association between phlebitis caused by enteric organisms and active intra-abdominal pathology. There were two deaths related to delayed or deferred surgery. Suppurative thrombophlebitis is a lethal, preventable nosocomial infection that requires urgent surgical intervention.