The effect of mental stress on coronary flow velocity reserve (CFVR) was examined in healthy men using transthoracic Doppler echocardiography. In the mental stress group (n = 31), CFVR was significantly reduced at 15 (to 3.3 +/- 0.8, p <0.001) and 30 (to 3.7 +/- 0.8, p <0.01) minutes after mental stress testing, compared with before mental stress (4.3 +/- 0.9), whereas it did not change in each of 3 measurements in control subjects (n = 10). Mental stress impaired coronary circulation even after a certain interval after the stress.