The aim of this study was to determine the diagnostic accuracy of myocardial perfusion SPECT (single photon emission computed tomography) with technetium labeling in patients with right bundle branch block (RBBB) and with left anterior hemiblock (LAH). One hundred seven patients (53 RBBB, 54 LAH) for whom coronary angiography results were available were selected. The gold standard for diagnosis was based on two coronary angiography criteria: a) stenosis equal to or greater than 50% in at least one coronary artery, and b) completely normal coronary angiography. The sensitivity of SPECT was approximately 90% in both RBBB and LAH. Specificity was 58% and 50%, respectively, for the first criterion, but was 85.7% and 87.5%, respectively, for the second criterion.