The purpose of this study was to evaluate the marginal sealing ability of Hipol composite resin. Using freshly extracted human teeth and 2% acquous methylene blue, the marginal leakage of dye in restorative materials such as Hi-pol, Adaptic, Nuvasystem, Epolite and Amalgam was investigated at 37℃ and under temperature cycling between 4℃ and 60℃. The results were as follows; 1. All the filling materials revealed the penetration of dye between cavity walls and restorations. 2. Hi-pol and Adaptic showed more marginal leakage than other materials and the degree of dye penetration in Hi-pol was similar to that of Adaptic. 3. Nuva system showed the least marginal leakage at 37℃ and under temperature cycling between 4℃ and 60℃. 4. Under temperature cycling, all materials showed a slight increase in marginal leakage except Epolite, which showed the greastest change in leakage.