Right ventricular myocardial infarction (RVMI) occurs rather rarely, under the mask of various diseases and is not easy to detect. Hypo-vate prognosis. Intravital diagnosis of RVMI was successful in 4 patients. Location of the lesion and its extent were determined. This article reports two cases of the four. The disease onset manifested with dyspnea, dry cough, attacks of night asphyxia then symptoms of right ventricular failure arose and intensified. The clinical picture, typical ECG signs suggested the RVMI diagnosis. However, its verification, precise localization and estimation of the lesion size were possible only after balanced radioventriculography.