Abstract: (1) Two commercial varieties of paeonia roots and their decoctions have been analyzed according to Dragendorff's method. Both of them contain a small amount of essential oil, fatty oil, resinous substance, sugar, starch, pectin, protein and benzoic acid. (2) The total solids of petroleum ether, ether and alcohol fractions extracted from the decoctions are greater than the corresponding fractions isolated from the crude drugs, but the nature of the corresponding extracts obtained from both is almost the same. (3) The decoctions and their petroleum ether, ether and alcohol fractions extracted from the two paeonia roots have been investigated by means of capillary analysis with some modifications. (4) The chemical constituents of Pai-shao and Cheh-shao are essentially the same, but differ in quantities: the content of benzoic acid is 1.09% in Pai-shao and 0.92°/o in Cheh-shao. (5) The capillary analysis data show that Cheh-shao seems to contain an additional colouring matter, which is soluble in petroleum ether or ether. It masks the fluorescence on the paper strip when the petroleum ether or ether fraction extracted from the decoction is examined under the ultra-violet light.