Objectives.: This study assessed the incremental value of technetium-99m myocardial single-photon emission computed tomography (SPECT) and simultaneous first-pass radionuclide angiography, when added to treadmill exercise, for prediction of the extent of coronary artery disease. Background.: Technetium-99m count statistics permit the simultaneous assessment of myocardial perfusion and function. However, whether this characteristic improves prediction of the extent of coronary artery disease remains unknown. Methods.: We studied 70 consecutive patients who had coronary angiography within 6 months of the scintigraphic study. All patients underwent a symptom-limited treadmill exercise test. Treadmill data were summarized using a previously validated score. Left ventricular ejection fraction and regional wall motion were evaluated from a first-pass radionuclide angiogram acquired at peak treadmill exercise in the anterior view. Perfusion was assessed visually. Extent of angiographic disease was expressed as the presence or absence of multivessel disease (more than two coronary artery territories with >50% stenosis) and as a score that reflects the location of severe (>75%) stenosis. Results.: Stepwise addition of scintigraphic data (perfusion first, followed by function) to the treadmill score showed significant incremental value for prediction of the angiographic score at each step; exercise ejection fraction alone was the strongest independent predictor. Discriminant accuracy for detection of multivessel disease was also improved by the addition of perfusion information to the treadmill score and addition of regional wall motion analysis to both of them. In this case, ejection fraction failed to show independent value. Conclusions.: The addition of simultaneously performed sestamibi perfusion SPECT and first-pass radionuclide angiography to the treadmill exercise test significantly improved prediction of the extent of coronary artery disease.