The effect of diltiazem hydrochloride on left ventricular function was examined in patients with and without angina pectoris. Left ventricular volume and function were measured by ultrasonic analogue converison system. In 12 patients without angina pectoris, a fall in systemic blood pressure, a decrease in heart rate, no change in EDVI [end diastolic volume index], an increase in ESVI [end systolic volume index], decreases in CI [cardiac index], EF [ejection fraction], normalized mean systolic ejection rate, SWI [systolic stroke work index] and W/min [work per minute of the left ventricle] but no change in systemic vascular resistance were observed following the i.v. injections of 40 .mu.g/kg. In 10 patients with angina pectoris, decreases in EDVI and ESVI, no change in CI, a tendency to increases in EF and normalized mean systolic ejection rate were observed following the administrations of the same dose. Changes in systemic blood pressure, heart rate, SWI, W/min and systemic vascular resistance were the same as those in patients without angina pectoris. The results indicate diltiazem-induced reduction in left ventricular function in patients without angina pectoris as opposed to improvement in left ventricular function in patients with angina pectoris.