A 32-year-old man was hospitalized because of cardiac tamponade with the thickened visceral and parietal pericardial layers. Marked high level of adenosine deaminase activity (ADA) in pericardial fluid strongly suggested the diagnosis of tuberculous pericarditis, which was later assured by positive smear and culture of the pericardial fluid for Mycobacterium tuberculosis. Before rigid adhesion of the pericardial space was established, pericardiectomy was easily performed with satisfactory improvement of the hemodynamic status and physical symptoms of the patient. The present case suggests the efficacy of early surgical intervention to tuberculous pericarditis when it shows a sign of rapid progression to constrictive pericarditis. Furthermore, high ADA in pericardial fluid might be an useful diagnostic modality for tuberculous pericarditis.