The sensitivities of dipyridamole stress thallium 201 single photon emission computed tomography (SPECT) and treadmill exercise testing in the detection of myocardial ischemia were compared. Thirty-eight patients with Kawasaki disease and 11 age-matched controls participated in the study. Fifteen of the 38 patients with Kawasaki disease had marked coronary artery stenosis (> 75%) in at least one vessel. SPECT scans were obtained immediately after dipyridamole infusion and 4 hours later. The sensitivity of SPECT for detection of coronary stenosis was 80% (12/15), whereas that of treadmill exercise testing was only 33% (5/15) (p < 0.001). Although the sensitivity of SPECT significantly exceeded that of treadmill exercise testing among patients with coronary stenosis in only one vessel (p < 0.05), such benefits were not found for patients with stenosis in two or three vessels. These findings suggest that dipyridamole stress SPECT has a higher degree of sensitivity in the detection of myocardial ischemia than does treadmill exercise testing, especially for patients with single-vessel disease.