The usefulness of isometric handgrip exercise in the assessment of left ventricular function was studied in 27 patients, all of whom had angiographically documented coronary artery disease. The effect of extensiveness of coronary disease and presence or absence of collaterals (both delineated by coronary arteriography) on the response to handgrip stress was also evaluated. Of 11 patients with a normal handgrip response, 4 exhibited a normal left ventriculogram and 7 were abnormal. Of these 7, 6 had inferior hypokinesis. Conversely, of 16 patients with an abnormal response to handgrip, 15 had abnormal ventriculograms. Of these, 9 had anterior akinesis. Of patients with a normal handgrip response 82% had two- or three-vessel coronary disease, and 94% with an abnormal response exhibited two- or three-vessel obstruction. There was no observed correlation between the presence or absence of collaterals and the response to handgrip. This study indicates that (1) handgrip stress, when combined with left ventriculography, often yields important additional information regarding the effect of localized contraction abnormalities on overall left ventricular performance; (2) the extent of coronary obstructive disease or the presence of collaterals per se do not appear to be the primary determinants of left ventricular performance; (3) it is possible that the location as well as severity and extent of left ventricular contraction abnormality may play an important role in determining overall left ventricular performance.