The decoction of the leaves of Nyctanthes arbor tristis Linn. (Harsingar) is widely used in Ayurvedic system of medicine for the treatment of sciatica, arthritis, fevers, various painful conditions and as laxative. In the present investigation, the water soluble portion of the alcoholic extract of the leaves was screened for some CNS activities (viz. hypnotic, tranquilizing, local anaesthetic, hypothermic, anticonvulsant), antihistaminic and purgative activities. The extract produced general depression of spontaneous motor activity, significantly increased pentobarbitone sleeping time though it had no effect on righting reflex. Furthermore higher doses of the extract abolished CAR without affecting motor coordination. Moreover the extract exhibited hypothermic effect and protected guinea pigs from histamine aerosol. These activities are common to major tranquilizers and support the usage of the plant by Ayurvedic physicians in aforementioned conditions. In addition significant purgative activity was also exhibited by the extract.