Objectives. The purposes of this study were to examine the effects of dipyridamole infusion on hemodynamic variables and to compare these changes with myocardial perfusion. Background. Dipyridamole stress testing with myocardial perfusion imaging is widely used in the assessment of patients with known or suspected coronary artery disease (CAD). Few studies, however, have correlated the hemodynamic effects of dipyridamole using invasive monitoring with perfusion patterns in patients with chest pain syndromes. Methods. Hemodynamic measurements were made in the cardiac catheterization laboratory with a Swan-Ganz thermodilution catheter before, during and after infusion of dipyridamole (142 μg/kg body weight per min for 4 min). Technetium-99m sestamibi was injected 3 min after the completion of the infusion. Results. There were 20 patients with and 6 without CAD, as demonstrated by angiography. Compared with baseline values, dipyridamole resulted in an increase in pulmonary capillary wedge pressure (54 ± 78% vs. 32 ± 26%, p = NS), cardiac index (36 ± 21% vs. 40 ± 18%, p = NS) and stroke volume index (16 ± 18% vs. 40 ± 18%, p = NS) and a decrease in systemic vascular resistance (22 ± 13% vs. 24 ± 11%, p = NS), aortic pressure (2 ± 9% vs. 0 ± 6%, p = NS) and pulmonary vascular resistance (19 ± 25% vs. 11 ± 32%, p = NS) in patients with and without CAD. The peak effect of dipyridamole on heart rate, systemic vascular resistance and pulmonary capillary wedge pressure was evident at 3 min after infusion in 70% of patients. Aminophylline, given to 20 patients, improved hemodynamic variables within 2 min. The single-photon emission computed tomographic sestamibi images were normal in the 6 patients without and abnormal in the 18 patients with CAD. Conclusions. Dipyridamole-induced coronary hyperemia produces mild hemodynamic changes in patients with and without CAD; these changes are at or near peak effect at 3 min after infusion and are rapidly reversed by aminophylline.