We compared the results of adenosine and bicycle exercise 99mTc-methoxy isobutyl isonitrile (MIBI) myocardial SPECT in 22 patients (18 males and 4 females, mean age 51 +/- 11 yr) with angiographically documented coronary artery disease (CAD). METHODS All patients were submitted on separate days to three intravenous injections of 99mTc-MIBI (20 mCi); one at rest, one during exercise and one during adenosine (140 micrograms/kg per min for 6 min with injection of 99mTc-MIBI at 4 min). A total of 484 myocardial segments were quantitatively analyzed. RESULTS Adenosine induced a significant increase of heart rate (94 +/- 16 bpm at peak versus 70 +/- 13 bpm at rest, p < 0.01). Systolic and diastolic blood pressure were not significantly different after adenosine infusion compared to rest. In all segments, a significant relationship between exercise and adenosine 99mTc-MIBI uptake was observed (r = 0.90, p < 0.0001). Concordance between the two studies for identification of perfusion status was observed in 438 (90%) of the 484 segments (kappa value of 0.81). Agreement on localization of the perfusion defect to a specific vascular territory was 92%. CONCLUSIONS Despite different hemodynamic effects, adenosine and exercise 99mTc-MIBI SPECT imaging provide similar information in the diagnosis and localization of CAD.