In 64 patients requiring cardiac catheterization for chest pain, echocardiograms showing anterior mitral leaflet and left ventricular cavity simultaneously were recorded. These were digitized and their first derivatives computed in order to study time relations between mitral valve and left ventricular wall movement in early distole. In 10 patients with normal left ventricular angiograms and coronary arteriograms, mitral valve opening began 1-1 +/- 9-3 ms (mean +/- SD) before the onset of outward wall movement, and reached peak opening velocity 2-0 +/- 13 ms after maximum rate of change of dimension. Virtually identical time relations were seen in 15 patients with normal left ventricular angiograms but with obstructive coronary artery disease (3-6 +/- 9-3 ms and 0-7 +/- 7-3 ms, respectively). These close relations were lost in patients with segmental abnormalities of contraction on left ventricular angiogram. In 19 such patients with normal septal motion, outward wall movement began 53 +/- 31 ms before the onset of anterior movement of the mitral valve leaflet, and this isovolumic wall movement accounted for 31 per cent of the total diastolic excursion. In 9 patients with reversed septal movement, these abnormalities were greater, 92 +/- 39 ms and 33 per cent, respectively, while in 11 patients with diffuse left ventricular involvement they were small, 5-5 +/- 13 ms and 3 per cent. Frame-by-frame digitization of cineangiograms was used to confirm these findings which appear to reflect an abnormal change in left ventricular cavity shape during isovolumic relaxation.