Background: One of the main goals of dental prosthetics is to achieve a high aesthetic demand for the patient through the selection and production of aesthetic restorations that encourage the use of ceramic and dental-coloured composite resins to mimic the colour and translucency of natural teeth. Objectives: Aimed to evaluate the effect of artificial accelerated aging on translucency of two aesthetic materials namely CAD/CAM, HT Zirconia and reinforced composite based materials at two different thicknesses. Methods: high translucent zirconia and reinforced CAD/CAM composite. A total of forty disks specimens, shade A2, were prepared from two different CAD/CAM materials and ordered into two groups (n=20) according to type of material. Then each group divided to 2 subgroups according to thickness 0.3 and 0.5mm (n=10). Evaluation of translucency parameter done before and after artificial accelerated ageing for 5 hours in an autoclave at 134°C, 0.2 MPa utilizing a spectrophotometer. the Translucency Parameter (TP) was determined TP=[(ΔL*)²+(Δa*)²+(Δb*)²]^1/2. Results: Regardless of thickness, Composite revealed statistically significantly greater mean TP than zirconia (P-value <0.001). Thickness had an impact on the translucency parameter of two materials. Within group comparisons revealed that for each of the two materials, 0.3 mm revealed statistically significantly higher mean TP than 0.5 mm (P-value <0.001). A statistically significant impact of aging on translucency parameter (P-value <0.001) was existing which aging showed statistically significantly decreasing in mean TP for both materials. Conclusion: the translucency parameter was significantly affected by type of material, thickness, and aging within the limitations of this study