The effects of nitroglycerin on left ventricular hemodynamics were determined in ten patients from biplane cineventriculograms and simultaneous pressure measurements. Before and after nitroglycerin (1.6 mg sublingually) the following parameters were measured: Systolic (PLV) and enddiastolic pressure (PLVED), enddiastolic (EDV) und endsystolic volume (ESV), cardiac output (SV), ejection fraction (EF) and ejection rate (ER), ejection time (tej), heart rate (HR), dp/dtmax, dp/dtmax Pi-Ped, maximal systolic wall stress (sigmamax), integrated systolic wall stress (sigma), outflow resistance (Rsys) and ventricular compliance (a). Nitroglycerin leads to a reduction of both, pre- and afterload, with a significant fall of PLV (10.8%), PLVED (21.8%), EDV (9.1%) ESV (13.3%) AND Rsys (14.4%). The changes of ventricular pressure and geometry result in a diminution of left ventricular wall stress (sigmamax- 11.8%, sigma - 26.4%), representing a decrease of calculated total oxygen-consumption of 11.5%. In six patients with reduced left ventricular diastolic compliance nitroglycerin leads to a remarkable increase of the compliance. This is probably due to the reversal of a latent ischemia by the decreased myocardial oxygen-consumption.