Some difficulties etiological diagnosis were presented in an example of two clinical cases. In the first patient with exudative pericarditis tuberculosis was determined in histopathological examination of lymph node (caseous necrosis). After antituberculotic treatment the majority of clinical symptoms was disappeared. In the second patient with chronic constrictive pericarditis the tuberculous etiology was accepted according to highly positive tuberculin reaction and signs of pericardial calcification. Patient was qualified to pericardiectomy.