For the dispensing of Kampo formulas, only an adult dose is described by conventional formulary. Therefore a child's dose is often prescribed by reducing instructions for the fraction-times of an adult dose. However, it is necessary to study whether the content of Kampo-extract pharmaceutical preparations at a child's dose, are similar to decoctions prepared by reducing the dose of crude drugs, and reducing the quantity of water by fraction-times. Therefore it was compared whether the constituents of a decoction liquid at an adult dose, were equal to those of a child's dose. In the decoction method of our clinic, adult doses are decocted with an initial 600mL quantity of water to half volume, as per the normal decoction method, whereas children's doses are reduced to 2/3 or 1/3 times that of adult dose, and decocted to half of the early-stage quantity of water that they are with adults. In the present study, three Kampo formulas which have been used frequently in our clinic and have different prescription weights i.e., Oren-gedoku-to (9g), Keishi-bukuryo-gan-ryo (20g), and Juzen-taiho-to (33g) were studied. When child and adult doses were compared, a difference was noted in pH, extraction rate and extracted constituents. Extraction rates for a child's dose of Oren-gedoku-to and Juzen-taiho-to were lower than that of an adult dose. Extraction rates of component gradients? ferulic acid in Oren-gedoku-to, pae-oniflorin in Keishi-bukuryo-gan-ryo, and paeoniflorin and liquiritin in Juzen-taiho-to? for a child's dose were lower than those of an adult dose. However, extraction rates of component gradients? albiflorin in Keishi-bukuryo-gan-ryo and albiflorin and trans-cinnamic acid in Juzen-taiho-to ? for a child's dose (quantity of 1/3 times) were higher than those of an adult dose. These results suggest that the content of a decoction, which was prepared by reducing an adult dose to the fraction-time of a child's dose, is not the same as reducing the amount of Kampo-extract pharmaceutical preparation to the fraction-time of a child's dose.