The congestive heart failure occasionally occurs in the patients with chronic pulmonary hypertension stewed from chronic pulmonary diseases. Since this type of the heart failure in generally incurable, it is clinically important to detect the cardiocirculatory disturbances in these cases before the clinical symptoms of the heart failure develop. Then, the cardiopulmonary functions, especially the circulatory dynamics, in chronic pulmonary hypertensive patients were examined in this study. Material and Method The patients employed in this study were 32 cases of chronic pulmonary diseases, consisting of 15 cases of chroinc pulmonary emphysema, 1 of emphysematous bullae, 6 of bronchiectasis, 1 of pulmonary fibrosis and 9 of pulmonary tuberculosis complicated with either extensive pleural scar, chronic pulmonary emphysema or bronchiectasis, or after the chest surgery. All the cases had pulmonary hypertension, which was proved by means of cardiac catheterization. The data in 25 cases of chronic pulmonary diseases and of normal pulmonary arterial pressure were used as control. The analysis of expired gas and blood gas was done with a Scholander gas analyzer and Van Slyke-Neill apparatus, respectively. The pH of blood was determined using a Cambridge pH meter with a glass electrode. The pressures in the central veins, right heart and pulmonary circuit were recorded through Stat ham P-23Db strain gauge manometer on Yokokawa photographic recorder, employing the level of the external jugular vein as a zero point. The cardiac output was determined by the direct Fick method. The circulating plasma volume and mean pulmonary circulation time (abbr. MCT) from main pulmonary artery or right ventricle to brachial artery were measured using Evans Blue (T-1824). The ratio of right ventricular residual volume to right ventricular end diastolic volume (abbr. RV/EDV) was determined by Ohashi method, a modification of Bing-Holt method. The total pulmonary vascular resistance was calculated by Aperia's formula.