Among non-invasive methods for the detection of coronary restenosis after successful transluminal coronary angioplasty, the contribution of exercise myocardial Thallium 201 tomoscintigraphy (MTS) was assessed in a prospective study involving 168 patients with a mean age of 56 (range 32-75) who had undergone 174 successful single vessel angioplasties (86 AIV, 35 Cx, 53 RC) with residual stenosis of 50% or less. After an interval of 6 +/- 2 months, patients were reassessed without treatment by a maximum exercise test (ET) combined with Thallium 201 MTS, 24 hours before follow-up coronary arteriography. Restenosis, defined by a greater than 50% loss of the gain achieved by the initial angioplasty, was seen in 53 patients (30.4%). MTS, with the exception of any necrosed area, was read as positive in case of reversible exercise hypofixation with redistribution. Sixty seven tests were positive, 49 corresponding with restenosis. Four were normal despite restenosis. The diagnostic values of the 3 methods of angina, ET and MTS were 0.43, 0.74 and 0.92 respectively for sensitivity, 0.89, 0.85 and 0.85 for specificity, 0.64, 0.68 and 0.73 for positive predictive value and 0.78, 0.88 and 0.96 for negative predictive value. In total, MTS at 6 months had the best sensitivity for the detection of coronary restenosis after single vessel angioplasty and an excellent negative predictive value (96% alone, 100% combined with ET), eliminating the need for coronary arteriography when it is negative.