Purpose The purpose of this invitro study was to evaluate the effect of different ceramic material types and preparation designs on the fracture resistance of occlusal veneers. Statement of the problem: Thin bonded posterior occlusal veneers constitute a conservative alternative to traditional complete coverage crowns in treatment of severely worn dentition. Materials and Methods: Sixty extracted human maxillary first molars were randomly distributed into two equal groups (30 teeth for each) according to the preparation design: Non-ferrule(NF) and Ferrule (F). Each of group was divided into three subgroups according to the type of ceramic materials: IPS e.max CAD (LD), Lava™ Ultimate CAD/CAM (RNC) and Vita suprinity® PC (ZLS). The occlusal veneers were cemented over their respective teeth with resin cement Total Cem automix. The fracture resistance was determined by using a computer-controlled material's testing machine with a load cell of 5 kN, and data were recorded using computer software Results: The mean values of Fracture resistance of the NF Group were (1730.0 ± 367.2, 1785.6 ± 604.1, 1860.5 ± 354.6) for the LD, RNC, and ZLS respectively. While the mean values of Fracture resistance of the F Group were (2082.2 ± 310.6, 1752.4 ± 654.8, 1750.5 ± 435.1) for the LD, RNC, and ZLS respectively. According to ANOVA test, there was no statistically significance difference regarding the two variables (Preparation design and material type) (P=0.570 and 0.639) respectively. Also, there was no statistically significant difference regarding the interaction between the two variables in this study (P = 0.262). Conclusion: Within the limitation of this study, it was concluded that, Occlusal veneers made of IPS e.max CAD, Lava Ultimate, and Vita suprinity, are of comparable strength and can be used as an alternative treatment for the severely worn dentition. Also, neither the material type nor the preparation design has effect on the fracture resistance of the occlusal veneers.