In a series of 120 hypertensive patients, 60 were found to have echocardiographic left ventricular (LV) hypertrophy (Devereux's method). Of these, 18 (30%) had typical stress-induced angina and underwent coronary angiography, which showed that 11 (61%) had normal coronary arteries, and 7 (39%) (p < 0.05) had coronary stenosis of the epicardial arteries. Stress-rest thallium-201 scintigraphy (Burow's quantitative method) yielded abnormal results in 21 of the 60 patients with LV hypertrophy. Five of 30 (17%) were asymptomatic, 14 of 18 (78%) had angina, and 2 of 12 (17%) had dyspnea on exertion. In 5 normal patients used as a control group, coronary flow reserve after administration of papaverine (10 coronary arteries) was 6.25 +/- 1.4 versus 3.7 +/- 0.8 in 10 thallium-negative, asymptomatic hypertensive patients with LV hypertrophy (p < 0.001). The mean coronary flow reserve of 21 patients with abnormal thallium-201 results was 2.71 +/- 0.96 (p < 0.01 compared with the group with normal thallium-201 findings) and 2.5 +/- 0.6 in the segments with lowest uptake (p < 0.05 compared with normal segments in these same patients). Thus, stress-induced angina pectoris in hypertensive patients with LV hypertrophy was due to small-vessel disease in over half of our patients (62%).