8 normotensive late pregnant women were examined before, during and after the intravenous administration of nylidrin (Dilatol) with the method of quantitative sphygmometry, the bloodless graphic registration of the arterial blood pressure and the direct electronic timing of pulse wave velocity. Systolic blood pressure remains unchanged; mean and diastolic blood pressure and total peripheral resistance decrease. Simultaneously heart rate, stroke volume and above all cardiac output increase. The hemodynamic mode of action of nylidrin is a favourable one in regard to the perfusion of tissues in pregnancy, because the fall of total peripheral resistance is much more pronunciated than the decrease of blood pressure. Therefore there are no objections to a tocolytic treatment with nylidrin in normotensive pregnant women on the part of cardiovascular system.