Purpose: To evaluate the effect of different CAD/CAM ceramic materials on the degree of conversion of two resin cements. Methods: A total of 60 disk-shaped ceramic specimens with 0.5 mm thickness were used for fabrication of 60 disk-shaped resin specimens of 0.5 mm thickness and 8 mm diameter and divided into three groups according to the type of ceramic material {IPS e.max (n=20), Ultra-translucent zirconia (n=20), Vita Enamic (n=20)}. Each main group was divided into two equal sub-groups according to the type of resin cement {Rely X Veneer light-cure (n=10) and Rely X Ultimate dual-cure (n=10)}. Degree of conversion (DC) was then measured. Data were collected and analyzed. Results: One-way analysis of variance (ANOVA) and Bonferroni's post hoc tests showed that IPS e.max CAD specimens exhibited statistically higher DC values than other ceramics for light-cure resin cement specimens. Ultra-translucent zirconia specimens exhibited statistically higher values than other ceramics for dual-cure resin cement specimens. Vita Enamic specimens presented the lowest values for both resin cements (P< 0.05). A significant difference was observed in all ceramic specimens with 0.5 mm thickness (P< 0.05). Conclusion: All ceramic materials provide clinical acceptable degree of conversion of both light and dual-cure resin cements.