Whether the combined analysis of rest 201 Tl and sestamibi uptake provides additional information regarding myocardial viability in patients with coronary artery disease is still to be investigated.To this aim we studied 22 patients with previous myocardial infarction and regional ventricular dysfunction by quantitative rest sestamibi and 201 Tl scintigraphy. All patients underwent revascularization, and echocardiography was repeated 11±2 weeks later. Concordant results were obtained in 80 of 105 dyssynergic segments. Fifty-one segments showed normal and 29 abnormal activity. Follow-up echocardiography showed increased wall motion contractility in 76% of segments with maintained 201 Tl and sestamibi uptake and in only 17% of segments characterized by subthreshold activities. Twenty-five segments, or 24%, showed sestamibi/ 201 Tl mismatch. Eleven of 12 segments with normal sestamibi/abnormal 201 Tl activity did not improve after revascularization, whereas 11 of 13 segments with abnormal sestamibi but normal 201 Tl showed postoperative improvement of regional wall motion.In patients with previous myocardial infarction, sestamibi and 201 Tl showed concordant results in most segments. However, in segments with mismatch a maintained sestamibi uptake was a poor indicator of tissue viability, whereas significant 201 Tl uptake reflected tissue viability in most segments.