Background Peritoneal tuberculosis and primary peritoneal carcinoma can both present as an abdominal mass and ascites with elevated serum CA125.The purpose of our study was to evaluate the clinical features of peritoneal tuberculosis,compare them with features of primary peritoneal carcinoma,and establish definitive diagnostic procedures.Methods We conducted a retrospective study in patients with peritoneal tuberculosis from January 1995 to October 2010 at Peking Union Medical College Hospital.During this time,the data of 38 patients with primary peritoneal carcinoma were reviewed.Results The median age was 34 years (range,19-80 years).The most common symptoms were abdominal distension (16/30,53.3％) and an abdominal mass (12/30,40.0％).The serum CA125 level was elevated in 25 patients (83.3％).The median level of cancer antigen CA125 was 392.5 U/ml (range,0.64-850.0 U/ml).Abdominal ultrasound revealed a pelvic mass in 25 patients and ascites in 20 patients.Diagnostic laparoscopy was performed in 15 patients (50.0％) and exploratory laparotomy was performed in 12 patients (40.0％),and 3 patients (10.0％) who underwent laparoscopy converted to laparotomy because of severe adhesions.The intraoperative findings were adhesions,multiple white tubercles,and ascites.Frozen tissue sections were obtained in 17 patients,and 14 of whom showed chronic granulomatous reactions.Final pathological examinations confirmed the diagnosis.Conclusions Peritoneal tuberculosis should be considered as a differential diagnosis,especially for young women with an abdominal mass,ascites,and elevated serum CA125 levels.Laparoscopy is a useful diagnostic method for peritoneal tuberculosis,and intraoperative frozen sections are recommended when the diagnosis is in doubt.