B Background: Nowadays, many people are very concern about performance especially in terms of the appearance of the teeth. Various attempts were made to improve the appearance of teeth by bleaching. Bleaching material used is carbamide peroxide and hydrogen peroxide. But the public doesn't know that bleaching may release free radicals which affect surface roughness of the composite restoration. Aim: The purpose of doing this research is to know the effect of carbamide peroxide (Opalescence) 20% and 35% against the surface roughness micro hybrid composite resin (Filtek TM Z250). Method: The design of this research is experimental laboratory. Samples of resin composite cylindrical with a diameter of 5 mm and 2 mm thick totaled 15 and divided into 3 groups (K1, K2, K3) and 5 of each group. Kl is the control group i.e without treatment, K2 is the application of carbamide peroxide 20%, and K3 is the application of carbamid peroxide 35%. The Group sampled K2 and K3 applied materials bleaching every day for 2 weeks (14 days) will be tested on the 7th and 14th day. Each group was tested with Mitutoyo Surfest 301 and results data will be tested statisticslly by One Way ANOVA followed by Tukey HSD test. Result: The results of statistical tests One Way ANOVA showed that have significant differences after 14 days (p<0.005 ) continued with Tukey HSD Test and showed that significance difference in K2 after 14 days (p>0,005) and have significant difference in K# after 7 days (p<0,005). Conclusion: Carbamide peroxide 20% make an increase in surface roughness of micrhoybrid composite resin significantly after 14 days and carbamide peroxide 35% make an increase in surface roughness of microhybrid composite resin siginficantly in 7 and 14 days.