Single crystal gammacamera and minicomputer were employed in 71 patients to determine left-ventricular ejection fraction (EF) (17 mCi 99mTc-HSA; 30 degrees RAO projection) by means of the first tracer passage. In 30 out of these patients, ventricular wall motion could be analyzed additionally because later on the gammacamera was equipped with a converging collimator. Comparison with cineventriculographically determined EF values revealed a good correlation (r = 0.91), not depending on left-ventricular wall motion pattern. Hereby, with first transit, high EFs were computed somewhat lower and low EFs were found somewhat higher. This non-limiting discrepancy is closely related to the influence of paracardiac "background"-radioactivity. Comparative analysis of segmental wall motion demonstrated agreement in 83% of the 90 segments examined. Therefore, it can be confirmed that performance of the first tracer passage for a evaluating segmental wall motion must not mandatorily be done with a multicrystal camera.