Purpose: The current study aimed to evaluate the marginal accuracy and microleakage of machinable laminate veneers. Materials and Methods: Twenty-four human maxillary central incisor teeth were collected and prepared (butt-joint preparation) to receive laminate veneers. They were divided into three groups (n=8) according to material of construction: Group I: IPS-Emax CAD, Group II: Vita Suprinity, Group III: Celtra-Duo. The veneers were milled from the blocks in a CEREC 3 Machine. All veneers were cemented with resin cement. All samples had been subjected to 1500 thermal cycles which are equivalent to one year and half of clinical use. Marginal gap (pre and post cementation) and microleakage were detected for all samples. Data were tabulated and statistically analyzed. Results: Regarding vertical marginal gap, E max CAD showed the highest mean value followed by Celtra Duo, while the lowest mean value was found in Vita Suprinity. The mean values before cementation were higher than after cementation. Regarding microleakage, the highest mean value was found in E max followed by Celtra Duo, while the lowest mean value was found in Vita Suprinity. Leakage at cervical margins showed higher mean values than incisal one. Conclusion: Under the test conditions, the following was concluded: Zirconia reinforced Lithium silicate restorations, particularly the partially crystalline form, introduced better marginal accuracy and microleakage than Lithium disilicate restorations. There is a direct correlation between marginal accuracy and microleakage.