Determination of right ventricular ejection fraction and volumes from radionuclide studies is cumbersome and is subject to considerable methodologic error. Further, assessment of regional wall motion has only infrequently been approached in a systematic way. A system of right ventricular ejection fraction and volume measurements is described that utilizes the previously validated single plane geometric method applied to first pass radionuclide angiocardiograms. Five right ventricular chords were defined and used to assess regional wall motion; normal values were obtained from 14 patients who were without demonstrable cardiac disease. Among 23 patients with anterior myocardial infarction, the right ventricular ejection fraction was within 2 SD of normal in 16; however, 3 of these patients showed regional wall motion abnormalities in the right ventricle. Of 21 patients with inferior myocardial infarction, right ventricular ejection fraction was reduced in 15; of the 6 with normal values, 3 had regional wall motion abnormalities as demonstrated by the chord shortening method. Of 21 patients with dilated cardiomyopathy, right ventricular function was abnormal in 20; the presence of a wall motion abnormality in the conus segment separated these patients from patients with right ventricular dysfunction after recent myocardial infarction. Thus: 1) right ventricular ejection fraction, volumes and wall motion can be assessed by a simple, geometric technique; 2) analysis of chord shortening by this method provides information unavailable from global ejection fraction data alone; and 3) the clinical correlates of these data will require further investigation.