Nylon microcapsules of sodium salicylate containing three different matrixes, acacia, gelatin and formalized gelatin, were prepared by interfacial polymerization and the effect of the matrix on the dissolution rate of sodium salicylate from its nylon microcapsule was investigated. The microcapsules were spherical and their particle diameter increased in proportion to the amount of matrix. The surface was different from each other according to the kind and the amount of matrix when observed by the scanning electron microscopy. The dissolution rate of sodium salicylate from its microcapsules was decreased by increase of the amount of matrix and the formalized gelatin most decreased the dissolution rate of drugs.