Purpose: Evaluating the effect of different computer aiding designing/computer aiding manufacturing techniques on marginal accuracy, color matching and retention of cemented versus screw retained implant-supported crowns. Materials and Methods: Thirty six zirconia implant supported crowns were constructed and divided according to mode of retention into two groups (n=18/group);GpI:Implants supported crowns cement retained to customized zirconia abutments. GpII : Implant-supported crowns screwed directly to implant analogs. Each of the two groups were further subdivided according to mode of veneering into three subgroups(n=6/group).(IA)Full Contoured cement retained zirconia crowns (IB)Solid Zirconia copings veneered by Hand layering&(IC)Solid Zirconia coping veneered by Heat pressed ingots.(IIA)Full contoured screw retained zirconia crowns(IIB)&(IIC)Solid Zirconia copings manufactured and veneered as cement retained but they were screwed directly to implant analog. Marginal accuracy, color matching and retention was measured. Results :Press veneered cement retained subgroup(IC)showed the biggest marginal gap value, while full contoured screw retained subgroup(IIA)showed the smallest. Cement retained hand veneered(IB)showed the highest statistically significant color matching acceptance(50% good, 16.67% fair,33.3%adjust).Screw retained group[II] showed statistically significant lower retention mean value than cement retained group[I].The highest statistically significant retention mean value was recorded by press veneered subgroups [C] . Conclusion: While cement retained showed better color matching and resistance to dislodgment than screw retained zirconia CAD/CAM implant supported crowns but the later showed better adaptation. Full contoured showed lowest marginal gap, hand veneered showed highest color matching acceptance and press veneered showed the highest retention mean values.