Polygalae Radix was used as diuretics, analgesics and expertorants in oriental medicine. The root of Polygala tenuifolia Willd. (Polygalaceae) is comprised saponin (Onjisaponin A,B,C,D,E,F and G) polygalitol, onsitin and sugars. The pharmacological action of crude Polygala-saponin (PS) obtained from the roots are studied. The following results were obtained; 1) The median lethal dose $(LD_{50})$ of PS in mice is presented 71.1mg/kg s.c. and 694. 5mg/kg p.o.. 2) PS demonstrated diuretic action of relatively long acting duration in mice. 3) The diuretic mechanism of PS was found due to inhibitory effect of renal tubular reabsorption of electrolytes and glomerular vascular dilatation. 4) The group, administered simultaneously PS and cefadroxil monobydrate was significantly increased with PS alone group on diuretic action. Synergistic effect cefadroxil monohydrate on the diuretic action of PS seems due to competitive inhibition of plasma protein binding with PS. 5) PS demonstrated analgesic action by the acetic acid stimulating method and Randall-Selitto test in mice. 6) PS presented antipyretic action against febrile treated with the typhoid vaccine. 7) PS was significantly prolonged against the hypnotic duration of pentobarbital in mice. 8) Onset time convulsion and death induced by picrotoxin and strychnine in mice were not delayed. According to the above results, the PS was identified as a pharmacological active component obtained from roots of Polygala tenuifolia Willd.