The haemodynamic effects of oral nifedipine 20 mg and molsidomine 4 mg were compared in 24 patients with coronary artery disease. Molsidomine unlike nifedipine caused a significant fall in mean pulmonary artery pressure and left ventricular end-diastolic pressure. Both drugs caused a significant and comparable reduction in systolic and diastolic blood pressure. Although only nifedipine significantly reduced systemic vascular resistance the difference between the drugs was not significant. The heart rate was significantly increased by nifedipine but not by molsidomine. The ejection phase indices were all increased by molsidomine and the increment in the mean normalized systolic ejection rate was significantly greater than that due to nifedipine. The left ventricular end-systolic volume index decreased significantly after molsidomine but not nifedipine. Neither drug significantly affected left ventricular end diastolic volume index, stroke volume index, maximal rate of rise of left ventricular pressure or left ventricular stroke work index.