Continuous ambulatory peritoneal dialysis (CAPD) was introduced to Japan ten years ago and was established as the treatment for end-stage renal disease along with HD. Although the incidence of peritonitis in CAPD has decreased by educating the patients and parents and the improvement of various devises of CAPD, peritonitis is still one of the major complications of CAPD. Fungus is a rare pathogen for peritonitis in CAPD, but it must be considered as a causative agent in cases of intractable peritonitis. This report describes the first case of Trichosporon beigelii (T. beigelii) peritonitis in CAPD in Japan. A nine year old boy with chronic renal failure due to bilateral vesicoureteral reflux was given CAPD treatment four years prior to admission. This patient had been admitted to our hospital frequently because of recurrent bacterial peritonitis. The peritonitis in CAPD was usually treated by changing the peritoneal fluid and antibiotic treatment. In this case T. beigelii was proved to be a pathogen of peritonitis by culture of CAPD fluid and also serum antibody titers. T. beigelii infection was successfully eradicated from the peritoneal cavity by administration of MCZ and by the removal of peritoneal catheter. The patient was switched from CAPD to HD. In the case of intractable peritonitis in CAPD, rare fungal pathogens such as T. beigelii must be considered as a causative agent.