The regional contraction patterns of the left ventricle, shortly after myocardial infarction, were assessed from computer-processed scintigraphic images and histograms of the first transit of an intravenously injected radionuclide bolus. Seventy-seven patients with documented myocardial infarction were injected with a compact bolus of 99mTc-pertechnetate which was coordinated with the ECG so that it arrived in the superior vena cava during diastole. Precordial activity during the initial passage was recorded in 50-msec intervals with a multicrystal scintillation camera interfaced to a dedicated minicomputer. Data frames of 4-7 cardiac cycles were summed into one representative cardiac cycle. In 73 of the 77 patients the images of the representative cycle, along with the corresponding time-activity curves, indicated wall-motion and stroke-volume anomalies corresponding with the electrocardiographic location of the infarct. This nontraumatic, essentially noninvasive technique permits serial examinations of the acutely ill patient for the spatial identification and estimation of suspected myocardial infarcts.