Myocardial performance in the intact human heart can be assessed from the analysis of ejection phase indices. Accordingly, among 20 consecutive patients who were studied by means of biplane left ventricular cineangio-cardiography, 18 were selected solely on the basis of high quality angiograms. The characteristics of left ventricular contraction were expressed quantitatively by the systolic ejection fraction, the mean velocity of circumferential fiber shortening at the left ventriculalr equator, and at several chords, the mean velocity of shortening of the hemichords and the mean normalized systolic ejection rate. All 18 patients had abnormalities of contraction based on the velocity of the hemichords. Both ejection fraction and mean normalized systolic ejection rate showed a low sensitivity in detecting depressed myocardial function in patients with segmental asynergy. Equatorial V(CF) provided additional information only when the affected areas were adjacent to the left ventricular minor axis. The sensitivity of this index was markedly increased by construction of several chords perpendicular to the left ventricular long axis (segmental V(CF)). However, when only one wall was affected, measurement of the velocity of shortening of the hemichords provided a better definition of the regional performance.