Left ventricular volumes were determined by means of ECG-gated RI angiocardiography, which were compared with volumes derived from contrast cineangiocardiography in 25 patients with various heart disease. There was a close correlation of end-diastolic and end-systolic volumes and ejection fraction between RI and contrast angiocardiography, although stroke volume yielded rather scattered values. In 46 of 52 patients with myocardial infarction left ventricular asynergy was demonstrated with our method. Mean velocity of circumferential shortening (mVcf) was exaggerated in patients with apical asynergy. mVcf derived from direct axis measurement yielded a higher value than that from area-length method. Left ventricular volume curve was constructed to obtain normalized systolic ejection rate during initial 100--200 msec after the start of ventricular depolarization. The index was in parallel to ejection fraction in every patient except in moderately severe hypertensive patients. End-diastolic compliance was calculated from Gaasch formula by obtaining pulmonary artery wedge pressure and end-diastolic volume, which was determined by injecting 99mTc pertechnetate into pulmonary artery through Swan-Ganz catheter. This way of access to patient with acute myocard infarction was most useful to evaluate the mechanism of elevated left ventricular end-diastolic pressure.