Stenotrophomonas maltophilia peritonitis in continuous ambulatory peritoneal dialysis (CAPD) patients is associated with poor prognosis and loss of CAPD catheter. S. maltophilia is one of the rarely reported microorganism in peritonitis. The case, 65 years old man with chronic renal failure who was followed for CAPD treatment for 3 years, presented with fever, abdominal pain, nausea, vomiting and cloudy peritoneal fluid. At our nephrology clinic, in the patient’s peritoneal fluid 5600/mm3 leucocyt was found and in his culture Stenotrophomonas maltophilia was isoleted. In blood analysis: leucocyt was18500 K/uL, CRP was 110,5 mg/L. In culture, microorganisms were sensitive to combination of ceftazidime and netilmicin and these drugs were applied to patient for 21 days and at the same time infectious parameters were followed. In conclusion, S. maltophilia is rarely the causative agent in peritonitis but it causes severe peritonitis. We want to emphisize that with proper antibiotic protocol, loss of catheter is prevented and complete treatment is possible in S. maltophilia infected CAPD patients.