Tl-201 imaging was performed in 194 patients who had undergone coronary angiography which had demonstrated coronary artery disease in 149 and normal coronary vessels in 45.91 patients had had previous myocardial infarction. Sensitivity for dipyridamole stress imaging was 92% for all 149 patients. 79% for the patients without previous infarction. Specificity was 81%. In a subgroup of 40 patients (32 patients with reversible Tl-201 defects and 8 normals), an additional dipyridamole wall motion study was performed in order to evaluate the correlation of Tl-201 perfusion abnormalities and ventricular function after dipyridamole. Only 19% of the patients had a dipyridamole-induced drop of global left ventricular ejection fraction, 31% showed dipyridamole-induced wall motion abnormalities; the predictability of specific vessel involvement by regional wall motion and regional ejection fraction assessment was 26% as compared with 70% for thallium imaging. Tl-201 perfusion defects after dipyridamole administration can also occur independent of ischaemia-induced changes in global and regional ventricular function. Coronary vasodilation with dipyridamole using Tl-201 imaging is a reliable alternative method in patients with coronary artery disease with an accuracy comparable to exercise studies with the advantage of not necessarily needing ischaemia as an endpoint of the test.