The capability of rapid (cine) MR imaging to quantitate left ventricular function was assessed in 13 normal subjects and in 15 patients with ischemic heart disease and regional wall-motion abnormalities proved by echocardiography and/or by contrast ventriculography. Fifteen to 20 MR images/cardiac cycle were acquired by using partial flip angles, short repetition times, and gradient-refocused echoes. Regional wall motion was assessed qualitatively in the equatorial left ventricular section by using the cine display and quantitatively by measuring myocardial thickness at end-diastole and at end-systole in six left ventricular segments in this plane. In normal volunteers wall motion was normal in all segments. Heterogeneity of systolic wall thickening was observed in normal subjects, ranging from 33% +/- 17% in the posteroseptal segment to 66% +/- 29% in the posterior segment. Overall systolic wall thickening was 48% +/- 28%. From the cinematic display of MR images, abnormal wall motion was observed in 40 of 90 segments in patients with ischemic heart disease, which correlated well with results of echocardiography or contrast ventriculography. Twenty-one segments were hypokinetic, 15 were akinetic, and four were dyskinetic. In patients with ischemic heart disease, percentage systolic wall thickening was 43% +/- 31% in the segments with normal wall motion, 6% +/- 18% in hypokinetic segments, -4% +/- 24% in akinetic segments, and -13% +/- 25% in dyskinetic zones. Absolute systolic wall thickening was less than 2 mm in 31 of 40 abnormal segments and was greater than 2 mm in only three. Rapid acquisition, improved temporal resolution, and the capacity for cine display make this new MR technique potentially useful not only for qualitative assessment of cardiac wall motion, but also for quantification of regional myocardial function.