Assessment of regional left ventricular function with first pass angiocardiography in the RAO view almost entirely depends on high image statistics, accurate border definition and background subtraction, as well as an analysis of so called functional images which regionally measure and illustrate functional change during heart action, such as regional ejection fraction images, regional ejection rate images and mean transit time images. During first bolus transit the multicrystal camera gives an average of 300,000 cts/sec (360 patients) allowing precise border definition because of steepness of count changes at the LV-border. A varying background adjacent to each border point and also over the LV is subtracted. Measurements of segmental hemiaxis shortening and of zonal ejection fractions in the three zones supplied by the major coronary arteries have been performed. Clinical applications comprise examinations at rest, peak exercise, after nitroglycerin administration and after bypass graft surgery (total 2400 studies). Wall motion measured by means of hemiaxis shortening (210 segments) showed good correlation with angiocardiography in 91% of segments with normokinesis, in 90% asynergic and 88% of hypokinetic segments. Functional images corrected false negative and false positive wall motion measurements. In another 44 patients after myocardial infarction, there was (after NTG-administration) a significant increase in hemiaxis shortening in asynergic segment, but not in dyskinesias. Exercise studies in 60 patients with wall motion disorders showed a significantly higher increase in global ejection fraction in patients with resting EF-values under 58% than above that value. If ejection fraction tended to increase more than 5 points, wall motion tended to improve at exercise and viceversa. Zonal ejection fractions after bypass surgery showed an average increase of 6.4 points (14%) if complete vascularization was performed, but no zonal increase or decrease when vascularization was incomplete or the zone included a previous myocardial infarction (scar formation).