Microleakage may be a major factor for failure of the crown. This may allow passage of microorganisms, by–products of food and salivary fluids into the tooth –cement interface which may lead to eventual loss of crown. To avoid microleakge and failure of crown, choice of luting agent is extremely important. So the aim of the study is to evaluate and compare the microleakage of glass ionomer luting cement (Fuji I), resin–modified glass ionomer cement (Fuji CEM) and resin cement (RelyX U200) when used for cementation of stainless steel crowns in primary molars. Material and methods: 42 extracted teeth were divided randomly into 3 groups of 14 teeth ,with crowns cemented with different cements as follows: Group 1 – Glass ionomer luting cement (GC Fuji I), Group 2–Resin modified glass ionomer luting cement, (Fuji CEM); Group 3 – Resin luting cement. (RelyX U200). Using image analysis system, microleakage measurements was done two times successively, and the mean value of the two measurements were computed. Results: The data was statistically analyzed by the one way ANOVA test and Post hoc Tukey test. Mean and standard deviations (SD) were calculated. The result of a present study were tabulated as,Group 1: Crown cemented with Glass Ionomer Cement (GC Fuji I). (n=14). Group 2: Crown cemented with Resin Modified Glass Ionomer Cement (GC FujiCEM) (n=14).Group 3: Crown cemented with Resin Cement (RelyX U200). (n=14). Discussion : RMGI has many superior properties when compare to conventional GIC like it is less erosive less dissolvable also has higher compressive and tensile strength. On other hand, with respect to conventional GIC, RMGIC has some disadvantages too, like dehydration shrinkage, volumetric expansion due to hydroplastic properties of resin, all these may happen after several months of insertion. Because of all these properties lone term dimensional stability and consistency of physical properties of RMGIC may turn into doubt