The purpose of this study was to evaluate the amount of marginal microleakage of 2 light curable GI cements(Fuji II LC & VariGlass), which contain some resin components. 4 volunteers kept on acrylic resin plates, which contained dentin disks with cavities filled with test materials for 2 weeks. The time when polishing was done(5 minutes and 24 hours after filling) and the use of protective agents were varied, so 8 groups with each 6 specimens were tested. After having specimens(disks with cavities filled with materials) penetrated with 1% Methylene Blue solution, specimens were stored in 40% nitric acid solution for 4 days to extract adsorbed dye material. Supernatants of centrifuged samples were diluted 5 times and Spectrophotometer was used to determine the degree of absorption. Dye concentration was calculated through the pre-obtained Linear Regression Curve. The results were as follows. 1. The best result was seen in groups (PF24, PV24) which were protected and polished 24 hours later and the opposite phenomenon was seen in groups(NF24, NV24) which were held without protection and polished 24 hours later. Groups polished S minutes later showed moderate leakage pattern. 2. Groups polished 5 minutes later showed similar leakage amount irrespective of using of protective agent. But statistically insignificant lower values were seen in VariGlass than in Fuji II LC groups, So It was considered that VariGlass may be more resistant to early moisture attack than Fuji II LC. 3. In groups polished 24 hours later, there was no significant difference between materials but was definitely significant difference according to the use of protective agent. If the cement in which polishing will be done 24 hours later, Protective agent should be used to cover the surface.