The purpose of this investigation was to study the preperty of flow for seven different impression materials presently available in KOREA. In this study ,200 grams of a load was applied at regular intervals. As the result of this study, following points were revealed in terms of flow property of respective materials. 1)Impression plaster and irreversible hydrocolloid impression materials were found to have insufficient working time due to their tendency to set rapidly after mixing. 2)Regarding to impresssion pastes, it was found that it has manifested an ideal flow property until 2 minutes after mixing. Clinically, this material seems to allow sufficient working time for its manipulation.