Objective — to define diagnostic criteria and optimal algorithm for exudative tuberculous peritonitis verification. Material and methods. There were 37 patients with tuberculous peritonitis and severe ascites as a leading clinical symptom who underwent examination and surgical treatment at the Department of Tuberculosis Surgery of the Moscow Research and Clinical Center for TB Control for the period 2009—2018. Results. Significant variability of laboratory and instrumental data in verification of exudative tuberculous peritonitis was revealed. Ultrasound and CT are available, fast, and highly informative methods of abdominal imaging which, may be decisive in the diagnosis. These methods are characterized by high informative value to diagnose ascites (100%) while this finding along with intra-abdominal lymphadenopathy (51.4-59.5%), heterogeneity and layering of the peritoneum (75.7%) suggests tuberculous lesion. Laparoscopy also has a great diagnostic value for visualization of effusion and focal tuberculous lesions of parietal and visceral peritoneum. Peritoneal biopsy reliably reveals classic tuberculosis granulomas and their equivalents (in cases of HIV infection) in the vast majority of cases (91.9%), while bacterioscopic examination (identifying acid-resistant mycobacterium) is informative in 75.7% of cases. Conclusion. Histological examination is the most reliable diagnostic method and mandatory measure for diagnosis of peritoneal tuberculosis. The presented diagnostic algorithm is valuable for fast diagnosis of the disease and timely prescription of etiotropic therapy.