To evaluate the safety and usefulness of myocardial thallium-201 scintigraphy after intravenous dipyridamole during the early post-infarction period, 35 patients under 60 years of age and with recent first transmural uncomplicated myocardial infarction (27 inferior, 8 anterior) were examined between the 5th and 13th day of hospitalization. Although four patients experienced angina and transient ischemic ST depression during the test, there were no serious complications. Patients were followed for a mean period of 11.4 +/- 6.3 months after hospital discharge. None of the patients experienced recurrent infarction and there were no cardiac deaths. In 11 patients there were reversible perfusion defects in areas different from those of myocardial infarction. Of these patients, seven (one with infarct vessel stenosis only and six with multivessel coronary disease) developed angina during the follow-up: five underwent coronary surgery because of severe angina refractory to full medical therapy. Out of the 24 patients without reversible perfusion defects, only two (with multivessel coronary disease) showed typical angina symptoms. The presence of redistribution on thallium scans was significantly more frequent in patients who developed a recurrence of angina over a period of 11.4 +/- 6.3 months of follow-up (P less than 0.0005). Thus dipyridamole-thallium 201 scintigraphy is a safe, non-invasive stress test which may be used early following uncomplicated myocardial infarction in order to identify patients at risk for the recurrence of angina.