37 patients with chronic cor pulmonale have been investigated with radionuclide first passage, microcatheter-technique, respiratory function investigation, furthermore blood gas analysis. Significant positive correlation have been found between the pulmonary circulation time and the pulmonary artery pressure; between the pulmonary mean transit time and the pulmonary artery pressure; furthermore between the pulmonary stagnation index was calculated for the characterization of peripheral pulmonary stagnation and the pulmonary artery pressure. Significant negative correlation have been found between the pulmonary circulation time, the pulmonary mean transit time and the vital capacity, the FEV1, furthermore the O2-saturation values. The authors establish, that on the base of the close correlations between the isotopic circulation parameters and the clinical data, the radionuclide first passage investigation is suitable for the demonstration of the current conditions of cardiopulmonary circulation.