Light-curing composite resin restorations with acid etching technique and bonding agents cannot completely reduce the degree of microleakage. One initial report by Dr. Mclean (1985) describing glass ionomers as Class V cavity liners suggested that this product was superior to a resin/dentin bond to avert marginal leakage under a light curing composite. In this study, Wu's silver staining technique was used to evaluate the effect of glass ionomer liner on microleakage of light curing composite-Silux. Twenty one caries-free human molar teeth were selected for study. The Class V cavities were prepared on the buccal and the lingual surface of each tooth. Teeth were divided into 3 groups. Group I: Scotchbond/Silux and Liner/Scotchbond/Silux. Group II: Scotchbond/Silux and Hybond. Group III: Liner/Scotchbond/Silux and Hybond. The degree of microleakage were evaluated with Dr. Going's method by three dentists. The results of this study indicate that Ketac bond Glass ionomer liner was ineffective as a restoration in resisting microleakage on the gingival wall of cavities.