A patient with constrictive pericarditis proceeded under the mask of polyserositis for a long time is reported in the article. Manifestation of disease with recurrent multiple effusion and unclear instrumental signs of constrictive pericarditis were initially followed by diagnostic searching for various causes of polyserositis. Cancer, tuberculosis and systemic connective tissue diseases as probable causes of polyserositis were excluded. Severe signs of right ventricular failure with edema of legs, as well as CT and MRI data were valuable to diagnose constrictive pericarditis while echocardiography was not effective. Pericardiectomy was performed to correct congestive right ventricular failure. Case report demonstrates difficult diagnosis of the cause of multiple effusion initially considered as polyserositis. No echocardiography data on pericardial constriction justifies cardiac MRI and chest CT in unclear cases of recurrent multiple effusion. Pericardiectomy is indicated if constrictive pericarditis is diagnosed.