We used first-pass radionuclide angiocardiography to assess filling fraction during the first third of diastole, peak filling rate and peak filling rate during the first third of diastole as indexes of left ventricular diastolic performance at rest and after upright bicycle exercise in 32 normal patients and 68 patients with coronary artery disease. The mean filling fraction was unchanged from rest to exercise in normal patients (47 ± 15% vs 46 ± 13%; NS). Even in 49 coronary patients with normal (⩾ 50%) ejection fraction at rest, filling fraction was less than that in normal patients at rest (35 ± 11% vs 47 ± 15%,p< 0.001). Despite similar resting heart rates, patients with coronary disease had lower (p< 0.001) peak filling rate and peak filling rate during the first third of diastole than normal patients. With exercise, filling fraction decreased (p< 0.001) from the resting value in coronary patients. These data suggest that (1) indexes of diastolic performance can be noninvasively assessed at rest and during exercise using first-pass radionuclide angiocardiography, (2) abnormalities in early diastolic performance are often present at rest in patients with coronary artery disease despite normal systolic performance, and (3) exercise-induced ischemia results in increased early diastolic dysfunction in patients with coronary disease.