This study compared prospectively the diagnostic value of dobutamine echocardiography and exercise myocardial scintigraphy for restenosis at 6 months after angioplasty of the left anterior descending artery. Forty-one patients aged 58 +/- 10 years, admitted to hospital for myocardium infarction (N = 22) or unstable angina (N = 19), with single vessel disease, were treated by angioplasty of one lesion of the left anterior descending artery after initial evaluation of the left ventricular ejection fraction by echocardiography. At 6 months, left ventricular function was reassessed by echocardiography, dobutamine echocardiography and exercise myocardial scintigraphy (Thallium 201) performed without treatment. Coronary angiography was performed at the same time and showed 8 restenosis (19.5%). Overall, in this series, dobutamine echo and scintigraphy had respectively a sensitivity of 37.5% and 75%, and a specificity of 97% and 70% (p < 0.02). Nine patients had left ventricular dysfunction unchanged compared with the initial measurement without viability in the territory of the left anterior descending artery with low dose dobutamine (group 1); thirty-two patients had improved or normal left ventricular ejection fraction with myocardial viability (group 2). In group 1, no cases of restenosis were detected by dobutamine echocardiography but_of them had myocardial scintigraphic evidence of ischaemia. In group 2, the sensitivity of the two techniques was comparable but dobutamine echo was more specific than scintigraphy (96 versus 75%, p = 0.03). In conclusion, dobutamine echocardiography may be indicated in the diagnosis of restenosis of the left anterior descending artery and in cases of viability in its territory. In its absence, myocardial scintigraphy seems to be preferable.