The acute effects of nifedipine (20 mg) on left ventricular diastolic function were investigated in 16 patients with chronic coronary artery disease by measuring left ventricular pressure with a manometer-tipped catheter and by measuring volume with cineangiography. Heart rates were maintained by right atrial pacing. Left ventricular peak systolic pressure (-15%; p less than 0.01 vs control) decreased significantly. With afterload reduction, left ventricular ejection fraction (+11%; p less than 0.01) increased. There was no significant change in left ventricular end-diastolic pressure. The diastolic peak filling rate of left ventricular volume significantly increased (+36%; p less than 0.05), whereas the time from end-systole to the peak filling rate remained unchanged. Administration of nifedipine did not improve left ventricular relaxation as assessed by the isovolumic pressure decay. There was also no significant change in the left ventricular diastolic pressure-volume relationship. We conclude that nifedipine improves left ventricular systolic function with afterload reduction but has little or no effect on left ventricular diastolic properties in patients with chronic coronary artery disease.