Peritonitis remains a major complication of peritoneal dialysis which is usually caused by saprophytic gram positive microorganisms originated from skin. Here, I report an unusual case of peritonitis due to Moraxella catarrhalis. A male, 59 age, on peritoneal dialysis modality because ESRD due to diabetic nephropathy was admitted to our hospital due to CAPD peritonitis. After initial empiric treatment and identification of this infrequent causer, he was submitted to two week antibiotic treatment with complete recovery and good prognosis. Peritonitis is the major cause of peritoneal dialysis failure which requires prompt recognition of the causative agent for successful treatment.