The aim of this study was to investigate the accuracy of quantitative one-day exercise-rest 99mTc tetrofosmin tomography in the identification of patients with suspected coronary artery disease (CAD) and in the detection of single stenosed coronary vessels. Sixty-one patients with suspected CAD and submitted to coronary angiography were examined. All patients were given 2 i.v. injections of 99mTc tetrofosmin, one at peak exercise (370 MBq) and the other (1110 MBq) at rest 3 hours after exercise (images 15-30 min after injection for both studies). All patients with CAD (> or = 50% luminal stenosis) (n = 50) had abnormal 99mTc tetrofosmin tomogram (100% sensitivity). Only one patient without CAD had abnormal 99mTc tetrofosmin tomogram (91% specificity). Overall sensitivity, specificity, and diagnostic accuracy in the detection of single stenosed vessels were 77%, 93% and 85%, respectively. No significant differences among single vascular areas were observed. Sensitivity and diagnostic accuracy in the identification of single stenosed coronary vessels were significantly higher (p < 0.05) in the patients with single-vessel disease (n = 21) than in those with multivessel disease (n = 29). Sensitivity, specificity and diagnostic accuracy in detecting single diseased vessels were similar in the patients without (n = 26) and in those with previous myocardial infarction (n = 35). The results of this study demonstrate that quantitative one-day exercise-rest 99mTc tetrofosmin SPECT imaging is a suitable and accurate technique to identify patients with suspected CAD and to detect single stenosed coronary vessels.