Abstract: Objective  To explore features of the plain CT scan in patients with tuberculous peritonitis.  Methods  Forty-six tuberculous peritonitis patients with data of abdominal plain CT scan were retrospectively reviewed，including 6 cases proven by postoperation pathology, 2 cases diagnosed by abdominal puncture, 4 cases confirmed by laparoscopy, and 34 cases identified by experimental treatment.The CT features of tuberculous peritonitis involved in parietal peritoneun, peritonealcavity，greater omentum, mesentery, and retroperitoneal space were observed.  Results  The main features in the plain abdominal CT scan of tuberculous peritonitis appeared as follows：①Thickened parietal peritoneum in 33 cases (71.7%)，including smooth in 27 and irregular in 6；②Ascites in 31 cases (67.4%)，of which 20 cases revealed a small amount of effusion；③Thickened greater omentum in 26 cases (47.8%)，including smear like shape in 22 and caked sign in 2；④Mesenteric thickening in 32 cases (69.6%)with concurrent small nodular shadows in 9 cases；⑤Enlarged lymph nodes in 16 cases (34.8%)；⑥Bowel  wall thickening in 1 case.  Conclusion  The main plain CT scan features of tuberculous peritonitis may appear as a small quantity ascites，smooth thickening and enhanced parietal peritoneum，thickened greater omentum with smear shadows，involvement of mesentery and enlargement of lymph nodes.The plain CT scan can provide important information for the diagnosis of tuberculous peritonitis.

Key words: Peritonitis,tuberculous/radiography, Tomography, Xray computed