Aim: To evaluate the clinical, radiological and microbiological properties of abdominal tuberculosis (TB) and to discuss methods needed to get the diagnosis.Methods: Thirty-one patients diagnosed as abdominal TB between March 1998 and December 2001 at the Gastroenterology Department of Kartal State Hospital, Istanbul, Turkey were evaluated prospectively. Complete physical examination, medical and family history, blood count erythrocyte sedimentation rate, routine biochemical tests, Mantoux skin test, chest X-ray and abdominal ultrasonography (USG) were performed in all cases, whereas microbiological examination of ascites, upper gastrointestinal endoscopy, colonoscopy or barium enema, abdominal tomography, mediastinoscopy, laparoscopy or laparotomy were done when needed. Results: The median age of patients (14 females,17 males) was 34.2 years (range 15-65 years). The most frequent symptoms were abdominal pain and weight loss. Eleven patients had active pulmonary TB. The most common abdominal USG findings were ascites and hepatomegaly. Ascitic fluid analysis performed in 13 patients was found to be exudative and acid resistant bacilli were present in smear and cultured only in one patient with BacTec (3.2 %). Upper gastrointestinal endoscopy yielded nonspecific findings in 16 patients. Colonoscopy performed in 20 patients showed ulcers in 9 (45 %), nodules in 2 (10 %) and, stricture, polypoid lesions, granulomatous findings in terminal ileum and rectal fistula each in one patient (5 %). Laparoscopy on 4 patients showed dilated bowel loops, thickening in the mesentery, multiple ulcers and tubercles on the peritoneum. Patients with abdominal TB were divided into three groups according to the type of involvement. Fifteen patients (48 %) had intestinal TB, 11 patients (35.2 %) had tuberculous peritonitis and 5 (16.8 %) tuberculous lymphadenitis. The diagnosis of abdominal TB was confirmed microbiologically in 5 (16 %) and histo-pathologically in 19 patients (60.8 %). The remaining nine patients (28.8 %) had been diagnosed by a positive response to antituberculous treatment.Conclusion: Neither clinical signs, laboratory, radiological and endoscopic methods nor bacteriological and histopathological findings provide a gold standard by themselves in the diagnosis of abdominal TB. However, an algorithm of these diagnostic methods leads to considerably higher precision in the diagnosis of this insidious disease which primarily necessitate a clinical awareness of this serious health problem.