Background/Aim: The purpose of this study was to evaluate pusled-field gel electrophoresis (PFGE) for distinguishing between relapse and reinfection of Staphylococcus aureus infections in patients on continuous ambulatory peritoneal dialysis (CAPD). Methods: Between July 1993 and May 1997, 4 patients with recurrent CAPD-associated infections caused by S. aureus we enrolled in this study. There were nine episodes of peritonitis, one episode of temporary double lumen catheter infection, and one episode of Hickman catheter infection. A total of eleven S. aureus isolates were collected from peritoneal fluid (n = 9) and blood (n = 2). PFGE typing was applied. Results: In our study, from PFGE typing, the 11 S. aureus isolates were classified into seven patterns. Antibiogram profiling classified only four patterns. Patient A had a reinfection by another strain of S. aureus, and patient B had three episodes of peritonitis caused by the same strain of S. aureus due to exit site infections. Patient C had two episodes of CAPD peritonitis caused by two different strains, respectively. Patient D had four episodes of S. aureus infection (three CAPD peritonitis and one bacteremia); the first two episodes of peritonitis were caused by an identical strain of S. aureus, whereas the subsequent two infections were caused by other organisms. Conclusion: PFGE has a high discriminatory power and can be an assistant method to antibiogram profiling for distinguishing relapse from reinfection in CAPD-associated peritonitis.