An heterogeneous group of 24 patients has been studied with 201Thallium myocardial scintigraphy after stress (MSS); has been used an electronic calculator which made it possible to increase the reliability of the method. Nineteen patients were males, 5 females; the average age were 51.7 years S.D. = +/- 7.9. The 201Thallium (2 mCi) is iniected through a Teflon cannula inserted in the forearm l' before the interruption of the stress test on the cycloergometer. After 10' tests are made in AP-LAO and LL view; a second test is carried out after an hour, and, if necessary, after 4-6 hours time. The results are interpreted as: a) positive: absence (++) or obvious defect in perfusione (+); b) negative: normal perfusion (-); c) questionable: activity not significantly reduced (+/-). In some cases, the Authors studied correlations and discordances between MSS and clinical, coronarographic and echocardiographic data. Has been considered moreover, the uptake's and release's variations of the radio-isotope in relation with experimental knowledge of myocardial extration and clearance. We conclude by emphasising the interest of this method and suggesting some practical consideration: 1) patients with negative MSS don't need coronarography; 2) positive MSS, but restricted deficit, good delayed reperfusion, good clinical pharmacological control would permit a delay of coronarography. 3) clear multiple deficit need coronarography; 4) usefulness of the MSS for long-term control of the evolution of coronary disease and of patients operated of aorto-coronary bypass.