Stress thallium-201 emission computed tomography (ECT) was performed for 24 patients with myocardial infarction for quantitative evaluation of regional thallium redistribution and washout. ECT was performed using a rotating gamma camera 10 minutes and 2.5 hours after thallium injection during maximal exercise. Three short-axis sections and one central long-axis section were selected for the circumferential profile curves. Redistribution (%) and washout (%) were calculated from the stress and redistribution profile curves in each section. These parameters were evaluated by comparison with regional wall motion on radiographic contrast ventriculography. Forty-eight of the 52 segments (92%) with normal thallium uptake showed normal wall motion. Among the segments with abnormal thallium uptake, normal or hypokinetic wall motion was observed in 12 of 13 segments (92%) with more than 20% redistribution and in 16 of 19 segments (84%) with 10-20% redistribution, while it was observed in only 15 of 36 segments (42%) without redistribution (p less than 0.001). Among 48 infarcted segments, 16 segments (33%) showed significant redistribution on ECT analysis. Normal or hypokinetic wall motion was observed in three of five segments (60%) with more than 20% redistribution, and in 10 of 11 segments (91%) with 10-20% redistribution, while it was seen in only eight of 30 segments (17%) without redistribution (p less than 0.005).