In order to complete previous results of the efficacy of the horse chestnut saponin escin, its activity was tested on two further models of inflammation: the rat serous peritonitis provoked by i.p. injection of formalin solution, and the rat serous pleurisy provoked by intrapleural injection of Evans Blue/carrageenan. The results showed escin to be an anti-exudative substance with regard to its exudation inhibitory effect determined by the reduction of exudative fluid. As to peritonitis the diminution of protein permeation into the abdominal cavity was determined: with increasing doses escin tended to prevent more efficiently the diffusion of small molecules than the permeation of large molecules. The hypothesis that escin has an effect on the vascular walls in the sense of a "sealing" effect on the capillaries was tested on the following model: the permeability of the plasma-lymph barrier of the hind leg of the rabbit was enhanced by injection of bradykinin. Escin antagonised the bradykinin effect dose-dependently determined by the depression of the raised lymph-flow by about 70%.