The comparative studies were made on Salicylamide, used individually and compounded with antihistaminics as regards. (1) the absorption rate through isolated rat small intestine (in vitro) (2) the absorption rate through rat small intestine (in vivo), and the following effects were found. 1. The Absorption velosity of 2 m Mole gm. of salicylamide in the small intestine were decreased, when the agents compounded with tripelennamine indicating the greatest absorption inhibition in the case of m Mole gm. of tripelennamine. 2. The Absorption velosity of 2m Mole gm. of salicylamide in the small intestine were decreased, when the agents compounded with diphenhydramine indicating the greatest absorption inhibition in the case of 2m Mole gm. of diphenhydramine. 3. The Absorption velosity of 2m Mole gm. of salicylamide in the small intestine were increased, when the agents compounded with chlorpheniramine indicating the greatest absorption augmentation in the case of 0.2m Mole gm. of chlorpheniramine.