Aim- The aim of this study was to evaluate and compare the effects of At-home bleaching and In-office bleaching on the flexural strength of commercially available Nanohybrid and Microhybrid composite resins. Methodology- A total of 60 samples of nanohybrid composite (n = 30) and microhybrid composite (n = 30) of standardized dimensions were prepared. The prepared samples were finished, polished and further stored in artificial saliva for 24 hours at 37oC. According to the bleaching process, the samples were divided into three groups: Group A (Control); Group B (At-home bleaching) and Group C (In-office bleaching). Each group was divided into two subgroups according to composite used as: Sub-group 1 (Nanohybrid) and Sub-group 2 (Microhybrid). The samples, 20 from each group (10 from each sub-group) were examined to evaluate the flexural strength. The collected data were tabulated and statistical analysis was performed. Result- A statistically significant reduction in flexural strength was observed for the nanohybrid composite when Group A1 (Control) (186.41+15.10) was compared with Group B1 (At-home) (137.27+14.17) and Group C1 (In-office) (143.65+11.20). For the microhybrid composite, there was a statistically significant difference seen for flexural strength when Group C2 (In-office) (174.78+21.89) was compared with Group A2 (Control) (136.83+13.24) and Group B2 (At-home) (151.90+17.79). Conclusion- Flexural strength was seen best for unbleached nanohybrid composite, whereas for microhybrid composite, in-office group exhibited highest flexural strength followed by at-home group