Coronary blood flow reserve (CFR) was assessed by transesophageal Doppler echocardiography in normal subjects (group A, n = 20), hypertensive non-left ventricular hypertrophy (non-LVH) patients (group B, n = 22), hypertensive patients with LVH (group C, n = 32) and coronary heart disease patients (group D, n = 33) with the volume sample placed at the bifurcation of the left main and left descending coronary artery. Coronary blood flow velocity (CBFV) was evaluated at rest, 2 minutes after dipyridamole (0.56 mg/kg, i.v.), and 2 minutes after aminophylline i.v. The ratio of dipyridamole to rest maximal diastolic velocity (D/R PDV) was considered the index of coronary blood flow reserve. It was found that D/R PDV was significantly less in groups C and D compared with that in groups A and B(D/R PDV, 1.84 +/- 0.57, 1.57 +/- 0.41 versus 2.59 +/- 0.70 and 2.22 +/- 0.58, respectively), with no difference in D/R PDV between groups C and D. Twenty-four out of 32 patients in group C with D/R PDV were less than 2.0 compared to 29 out of 33 patients in group D (P > 0.05). Significant negative correlation was found between D/R PDV, D/R PSV and interseptal thickness, left ventricular mass index in hypertensive patients. These data show that impaired CFR in hypertensive patients with LVH is comparable to that in patients with coronary heart disease.