This study was conducted to assess the fracture resistance of lithium disilicate (IPS E.max CAD) crowns compared to zirconia reinforced lithium silicate (VITA SUPRINITY) ones. According to the sample size calculation, a total of twenty crowns were constructed. The samples were divided into two equal groups, ten samples each according to the type of material used: i. Group (E): Ten crown samples (n=10) fabricated of IPS E.max CAD. ii. Group (S): Ten crown samples (n=10) fabricated of VITA SUPRINITY . A stainless steel die was custom made to simulate a tooth preparation for a ceramic crown of a mandibular first molar, 6-mm occluso-gingival, 8-mm cervical diameter, 6mm occlusal diameter and a total occlusal convergence of 16o with a circumferential 1mm shoulder finish line configuration. The occlusal surface shoed 2 slopes: 1 buccal and 1 lingual where the angle in between was 130o using a custom V-shaped metallic device. The stainless steel die was then duplicated into twenty epoxy resin dies using Silicone impression material. The stainless steel die was scanned by Cerec Bluecam then crowns were milled by cerec MC XL device by using the “IPS E.max CAD” and “VITA SUPRINITY” blocks. After milling, the crowns were finished, polished and glazed prior to the crystallization process. The crowns were then seated on their corresponding dies and cementation was made by using Rely-x Unicem adhesive resin cement. The samples were maintained under a constant pressure of 2 Kg using a specially designed loading device to standardize the load applied during cementation procedure. All samples were subjected to fracture resistance testing under a compressive load at the center to their long axis using computer controlled universal testing machine with a load cell of 5 kilo newton (KN) and at a crosshead speed of 1 mm/min. Data was collected, tabulated and statistically analyzed. The fracture patterns and failure mode of all samples were then examined photographically using a digital camera The following results were obtained: The results of the fracture resistance testing for the samples of group (E) IPS E.max CAD crown and the group (S) VITA SUPRINITY showed that there was no statistical significant difference between the two groups where the mean values were ((1767.88±258.55 N) and (1505.73±91.48 N) respectively at p=0.065 . Both materials showed favorable and unfavorable pattern of failure.