The ability of myocardil contrast echocardiography to measure coronary flow reserve was studied in 19 patients with the use of sonicated iopamidol and papaverine as a coronary vasodilator. The studies were performed on patients undergoing diagnostic cardiac catheterization. Left anterior descending coronary artery minimal cross-sectional area was determined by quantitative coronary arteriography and ranged from 1.0 to 10.3 mm2. Intracoronary contrast echo injections were performed before and after papaverine administration. Background subtracted peak contrast intensity in the interventricular septum was measured and the ratio of postpapaverine to prepapaverine peak intensity was calculated. Linear regression of this ratio against cross-sectional area revealed an r value of 0.49 (P=0.03). The ratios of post- to prepapaverine intensities were not useful to disciminate patients with extremely small (less than 2 mm2) from those with larger cross-sectional areas. We conclude that a hyperemic reaction might be visualized in patients with coronary artery disease with the use of myocardial contrast echocardiography.