Introduction: Dental Caries is a widespread condition that requires attention however; its treatment remains a challenge in terms of child behavior management. Aim: To evaluate and compare fiberglass and zirconia crowns with stainless Steel crowns laboratory as full coverage restoration for deciduous molars of children. Materials and Methods: This study was conducted to evaluate and compare three types of crowns. It was carried out on 30 mandibular primary molars, 15 mandibular first primary molars for microleakage test and 15 mandibular second primary molars for crown fracture resistance test for three crown types. Results: In laboratory evaluation: the microleakage test results showed that there was a clear highly significant difference between the studied groups for the area (p< 0.0001). the fracture resistance test results showed that there was a clear significant difference between the studied groups for the Fracture Resistance test (p< 0.001). Conclusion: The accepted standard for posterior full coverage restorations in primary molars is still stainless steel crowns, followed by Zirconia crowns and fibreglass crowns come next.