Background: Monolithic zirconia have been developed with high strength and better esthetics. However studies on their strength and surface roughness after occlusal adjustment and subsequent modification are few. Aim: The aim of this invitro study was to evaluate the Effect of Different Surface Modifications on the flexural Strength of Monolithic Zirconia. Materials and Methods: A total of 30 monolithic zirconia specimens were fabricated from zirconia discs with the aid of CAD/ CAM, followed by sintering. Samples were randomly allocated into three Groups (n = 10) each. Group G: Glaze, Group GGR :Glaze-Grind-Reglaze, Group-PGR: Polish-Grind-Repolish. Samples of Group GGR and PGR were mounted on customized apparatus for grinding and surface modifications were performed for each Group according to the group allocated. Flexural strength of all the groups were determined by using Universal testing machine. The collected data was statistically analysed using unpaired “t” test and One way ANOVA- F test. P values less than 0.05 were considered to be statistically significant in all tests. Results: The mean flexural strength of the Group G was higher followed by Group PGR and GGR. Conclusion: Grinding decreased the flexural strength. Repolishing subsequently seems to be better than reglazing in terms of strength. However, it is impossible to create a original surface after grinding by reglazing or repolishing.