Aim of the study: evaluation optical properties (color and translucency) of zirconia core with different veneering techniques, using lithium disilicate glass ceramic as control.Material and methods: A total of twenty all-ceramic specimens in the form of discs (10 mm diameter and 1.5 mm thickness) were fabricated using a Teflon mold. The specimens were divided into two main groups, according to ceramic composition and fabrication techniques. Group 1: IPS e.max CAD for core construction and IPS e.max Ceram for layering technique, were its veneering material, (control group) (n=5), Group 2: IPS e.maxZirCAD block was the core material.(n=15) ,(Gr 2) was further subdivided into three subgroups representing the three different veneering techniques. Sub--group-I: Layering technique, using IPS e.maxCeram , (n=5). Sub-group-II: Press-on technique, using IPS e.maxZirPress glass ceramic, (n=5).Sub-group-III: CAD-on technique, using IPS e.max CAD, (n=5).a spectrophotometer was used in the measurements the color and translucency.Results: Control showed the statistically significantly highest mean translucency. This was followed by layering technique. CAD-on technique showed statistically significantly lower mean value. Press-on technique showed the statistically significantly lowest mean translucency. Press-on technique showed the statistically significantly highest mean (ΔE). This was followed by CAD-on technique. Layering technique showed the statistically significantly lowest mean (ΔE).Conclusions: 1- Regarding to lithium disilicate glass-ceramic block with CAD/CAM technique veneered with layering technique, was the most transparent. 2. Zirconium oxide block with the CAD/CAM technique, which veneered with three different veneering techniques: layering technique was the most acceptable system regarding translucency and color changes (ΔE), compared to CAD-on and press-on techniques.