Objective: To study the effect of two finish line configurations and two different types of ceramic materials on the vertical marginal gap distance and fatigue resistance of bonded posterior occlusal veneers.Materials and Methods: Eighteen extracted human mandibular molars were distributed into three equal groups according to the ceramic material: teeth were left intact to serve as control in the fatigue and fracture test (Group I (C)), teeth were prepared to receive IPS e.max occlusal veneers (Group II (E)), teeth were prepared to receive LavaTM Ultimateocclusal veneers (Group III (L)).Each of group II (E) and group III (L) were subdivided according to the finish line configuration into 2 subgroups: teeth were prepared with bevel finish line (Subgroup 1 (B)),teeth were prepared with rounded shoulder finish line of thickness 1mm (Subgroup 2 (S)). The vertical marginal gap distance was measured after cementation using a Scanning electron microscope connected to a computer. Mechanical ageing was performed for 10,000 cycles. Then fracture resistance was determined in a universal test machine. Results: For the bevel finish line, e.max recorded the highest mean marginal gap value (47.5±8.8 μm) compared to the LavaTMUltimate (46.5±14.8 μm), no statistical significant difference was found between them at P=0.513.For the rounded shoulder finish line,e.max recorded the highest mean marginal gap value (71.1±6.1 μm) compared to LavaTMUltimate (62.9±23.6 μm), no statistical significant difference was found between them at P=0.827.For the fracture resistance with both finish lines, no statistical significant difference was found between the two ceramic materials and control group.Conclusion: Occlusal veneers were found to be a successful mean of restoring erosive or attrite posterior teeth regarding marginal fit and fatigue resistance.