Objective: Mechanical properties enhancement of luting materials Used for Ceramic Laminate Veneers Cementation may affect the performance and the durability of esthetic restorations. The present study was performed to evaluate the Degree of Monomer Conversion of three different light polymerized resinous materials. Materials and Methods: Forty five ceramic slices of shade A2 were machined from low translucenct (LT) IPS Emax CAD blocks (n=45)using (Isomet 4000) sawing machine cutting at a speed of 2500 rpm with water cooling, the block were sliced to a uniform standard thickness of 0.5 mm. IPS Emax CAD slices were covering three resinous materials, RelyX Veneer, filtek Z350xt flowable composite and preheated  filtek Z350xt composite at 68°C, cured for 30 seconds and then separated from the slices, the 45 specimens were then divided according to the used luting material into three groups (n=15), the samples then prepared for analysis by Fourier Transform Infrared Spectroscope, uncured cement samples were also subjected to analysis. One-way ANOVA followed by Tukey's post hoc test was used to study the effect of resinous material on degree of conversion.The significance level was set at P<0.05. Results: The highest mean value of DC was recorded for Rely X Veneer resin cement, followed by flowable composite, while the least DC was recorded for the preheated composite. Conclusion: Both light cured resin cement and flowable composite were superior to preheated composite regarding their degree of monomer conversion.