Aim: Formulation of approaches to differential diagnosis and treatment policy for subacute infectious endocarditis (SIE) when it is masked by another monoorganic or systemic disease.
Materials And Methods: The course of SIE was analysed in 132 patients of whom 74(56%) had erroneous admittance diagnoses. Rheumocarditis was not confirmed in 34 patients, 24 patients had nonspecific reactions masking SLE (4 cases), glomerulonephritis (7 cases), myocarditis (4 cases), hemorrhagic vasculitis, nodular periarteritis, polymyositis (9 cases).