The effect of nifedipine on the ejection flow pattern in the left ventricular outflow tract was observed using pulsed Doppler echocardiography in 6 patients with hypertrophic cardiomyopathy. After sublingual administration of nifedipine (10 mg) to 1 patient, the turbulent ejection flow pattern became more marked and increased in duration compared with the initial state. An increase in turbulence in the left ventricular outflow tract may increase the pressure gradient between the left ventricle and the aorta. Nifedipine appeared to have the potential of adverse action on left ventricular outflow obstruction.