Experimental work has shown that even small reductions in myocardial perfusion impair contractile performance. We, therefore, studied the relationship between regional perfusion, assessed by thallium-201 scintigraphy and segmental wall motion, quantitated on biplane contrast ventriculograms, in patients with coronary artery disease. We evaluated 270 segments in 54 patients, including 27 without evidence of myocardial infarction. Most normally perfused regions (125 of 140) contracted normally, whereas those with scintigraphic defects at rest were usually asynergic (42 of 46). Surprisingly, 57% (48 of 84) of regions with exercise-induced perfusion defects were also asynergic, including 48% (25 of 52) of those in patients without myocardial infarction. In 22 patients who had intervention ventriculograms, improvement of perfusion abnormalities at rest correlated closely with reversibility of asynergy. Although there was an association between the location and severity of coronary artery stenosis and segmental wall motion, myocardial perfusion during exercise was a significantly better predictor of asynergy. These findings suggest that resting asynergy may occur even in patients without previous infarction, predominantly in regions with jeopardized perfusion. Asynergy in regions with exercise-induced perfusion abnormalities may, therefore, be an indicator of resting ischemia and may be reversible by coronary artery revascularization.