Phasic coronary artery flow velocity was recorded in 14 patients with aortic regurgitation (AR), 4 with aortic stenosis, 61 with other heart diseases and in 2 normal subjects by means of a bidirectional Doppler flowmeter catheter. The normal pattern of the phasic coronary artery flow velocity was characterized by a small forward flow during systole (S wave) and a large forward flow during diastole (D wave). The phasic coronary artery flow velocity in patients with AR showed increased S wave and decreased D wave. The area under the S-wave curve divided by the area under the D-wave curve (S/D ratio) in patients with AR increased (left coronary artery flow velocity 0.66 +/- 0.39, p less than 0.05; right coronary flow velocity 0.79 +/- 0.36, p less than 0.01) as compared with the S/D ratio in patients with other heart diseases (left coronary flow velocity 0.32 +/- 0.12; right coronary artery flow velocity 0.38 +/- 0.17). There was a tendency toward a relative positive correlation between S/D ratio values and AR cineangiographic grades. Decreased S/D ratios were observed in 4 patients with aortic stenosis. It is believed that no reports exist on phasic coronary flow velocity recorded in conscious patients who had aortic valve disease.