Aim: To evaluate the microleakage of the glass carbomer cement with and without protective surface coat in primary molars and to compare it to conventional glass ionomer cement. Materials and Methods: Forty sound primary molars were included in the study. They were divided into two groups (n=20) according to the restorative material tested. Group A (experimental group): Teeth were restored using glass carbomer cement, and group B (control group): Teeth were restored using conventional glass ionomer cement. Then each group was further subdivided into two sub-groups according to the presence of surface coat. After teeth restoration, they were immersed in methylene blue solution for 24 hours then they were sectioned longitudinally into two equal halves and tested for microleakage. Results: There was a statistically significant difference between the microleakage scores of glass carbomer cement with surface coat (sub-group A1) and without protective surface coat (sub-group A2) in favor of sub-group A1. However, there was no statistically significant difference between the microleakage scores of conventional glass ionomer cement with surface coat (sub-group B1) and without protective surface coat (sub-group B2). By comparing the 4 sub-groups, sub-group A1 showed the lowest microleakage score, while sub-group A2 showed the highest score with statistically significant difference. Conclusion: Surface coat when added to the glass carbomer cement yields less microleakage than the unsealed glass carbomer and conventional GIC.