23 patients with coronary heart disease (11 with angiographically normal and 12 with depressed left ventricular function) were studied by m-mode echocardiography before and after handgrip. The following results were obtained: 1. There were statistical significant differences in enddiastolic volume, ejection fraction, and circumferential fiber shortening between the two groups. 2. Isometric exercise (handgrip) did not alter left ventricular dimensions or contractility, if mean values were calculated in both groups. 3. The majority of patients with compromised left ventricular function at rest, however, responded to handgrip by increasing their enddiastolic volume, apparently using the diastolic volume reserves. Ejection fraction and circumferential fiber shortening remained constant. 4. The majority of patients with angiographically normal left ventricular function at rest, on the contrary, displayed augmented contractility under handgrip. Only 4 out of 11 patients with proximally located, high-degree lesions and inadequate collaterals responed to isometric exercise with a reduction of ejection fraction and circumferential fiber shortening.