Polyamide microcapsules were designed for a sustained drug release. As a model, riboflavin was e no apsulated in polyamide microcapsules. Polyamide microcapsules were prepared from thiamines and acid bichlorides by the interfacial polycondensation reaction. The diamines used in ttlis works were ethylenediamine and 1, 6-hexamethylenediamine. Sebacoylchloride and teruphthaloylchloride were employed as acid bichlorides. The following parameters were studied; the release of several kinds of polyamide microcapsules , the various concentrations of diamines and acid dichlorides ; the various concentrations of surfactants : the various pH range of sink solution during the dissolution test. The release amount of riboflavin from aromatic polyamide micrcapsule was higher than that of aliphatic polyamide microcapsule The release rate of riboflavin from the polyamide microcapsule was decreased with increase of concentration of thiamines, arid dichlorides and surfactants which is used for preparing polyamide microcapsule. Release riboflavin from polyamide microcapsule was lower at pH 7 than pH 2 in sink-solution for dissolution test.