The noninvasive detection of restenosis is clinically important for the subsequent management of patients in whom percutaneous transluminal coronary angioplasty (PTCA) has been performed. The aim of this study was to compare the diagnostic value of dobutamine stress echocardiography (DSE) and stress 201Tl single-photon emission computed tomography (SPECT) for detecting restenosis after PTCA. Fifty-three consecutive patients referred for the evaluation of possible restenosis or whom had been scheduled for follow-up study underwent DSE a mean of 5 months after angiographically successful PTCA. Dobutamine was infused incrementally under two-dimensional echocardiographic imaging. The left ventricle was divided into 16 segments and grouped into three coronary vascular territories. Rest, low-dose, and peak-dose images were digitized and displayed in a quad-screen format. Positive findings for restenosis were defined as new or worsened wall motion abnormality at a previously dilated vascular territory. All but one patient underwent SPECT. Positive findings for restenosis were defined as the presence of redistribution. All patients underwent quantitative coronary angiography after two tests. Restenosis was angiographically demonstrated in 23 (43%) of 53 patients and 25 (42) of 59 vessels. The sensitivity of DSE and SPECT for detecting restenosis was 78% and 74%, specificity was 93% and 93%, and accuracy was 87% and 85%, respectively. In a total of 59 vascular regions, DSE was 76% sensitive and 94% specific for detecting individual restenosis. It is concluded that DSE is comparable in diagnostic accuracy to SPECT for detecting restenosis in patients after PTCA.