Intra-abdominal abscess is an uncommon complication of continuous ambulatory peritoneal dialysis-associated peritonitis. A 44-year-old female was on continuous ambulatory peritoneal dialysis (CAPD) for two years because of hypertensive end-stage renal failure. She had developed acute peritonitis that relapsed four times despite appropriate antibiotic treatment. The patient admitted to our clinic with nausea, vomiting, abdominal pain, diarrhea and high fever. C-reactive protein was 41 mg/dL (ref: 0.0-0.8); WBC count in peritoneal fluid was 2500/mm3 and 80% of these cells were polymorphonuclear leukocytes. WBC count in blood was 15 300/mm3 (ref: 3.5-11). Antibiotherapy was started, but clinical and laboratory findings did not show regression. Abdominal ultrasound was helpful for the diagnosis of abscess. Peritoneal catheter was removed and clinical and laboratory findings then improved. Considering this case, we think that in patients with frequently relapsing peritonitis not cured by antibiotic terapy, intra-abdominal abscess must be investigated at an early stage.