Abstract: A new method for assay of santonin from Artemisia incana Keller was described which was suitable for analysis of the herb or its lime water extracts.The procedure of the method was outlined as follows. 0.25gm.of sample was extracted with lime water and the calicum santonate was adsorbed by 1.0gm.animal charcoal,the calicum santonate in animal charcoal was acidified with hydrochloric acid and the free santonin extracted with chloroform and then estimated colorimetricaly with FeCl₃ in sulfuric acid. The average deviation of the method was estimated below 0.0176%. The analytic result of the same sample of the new methods and A.O.A.C.method(1945) are in close agreement.