Peritonitis is an important cause of morbidity and technique failure in peritoneal dialysis. Herein, we report peritonitis related to Acinetobacter lwoffi in two patients on peritoneal dialysis. The first case is a 63-year-old patient treated by automated peritoneal dialysis admitted with abdominal pain. The peritoneal effluent White Blood Cells count consisted of 280 cells/mm3. Then culture identified a multisensitive Acinetobacter lwoffi. Treatment with ceftazidime and ciprofloxacin had been started. The control dialysate culture was sterile after three weeks. The second patient is a 59-year-old female admitted because of diffuse abdominal pain and cloudy dialysate. The peritoneal effluent White Blood Cells count consisted of countless leukocytes, with predominantly polynuclear and culture identified Acinetobacter lwoffi. He received intraperitoneal ceftazidim and amikacin for three weeks. The control dialysate was sterile. Acinetobacter lwoffi is a rare cause of peritonitis and it can be treated successfully with early recognition and appropriate antibiotic therapy based on culture instead of catheter removal.