Discolouration of microhybrid composite resin is a common problem faced by both dental practitioners and patients. The accumulation of plaque, penetration of colourant particles from foods and beverages, dietary habits and the smoothness of restorations have been known to influence the quality of the aesthetic restoration. The purpose of this study was to determine the effects of polishing systems on surface roughness that led to discolouration of the microhybrid composite resin. Methods: Forty five samples of microhybrid composite resin (Filtex Z100) restorations were polished with two different polishing systems; one-step polishing (OP) system on the distal surface and multiple-step polishing (MP) system on the mesial surface. All samples were then immersed in two common beverages: black coffee and cocoa, for 20 minutes daily throughout 28 days of the experimental period. Results: Data on visual colour measurement and spectrometer colour spectrum was subjected to one-way ANOVA test at a significance level of 0.05. Both solutions were found to cause a significant colour change (p=0.0195) on the microhybrid composite resin. Black coffee solution obtained the highest score (71.6) of visual colour change and the lowest reflectance value (62.818) on the distal surface. Surface roughness evaluation using a scanning electron microscope (SEM) had presented that both polishing systems used produced low level of surface roughness. Conclusion: Although MP system produced a smoother surface compared to OP system, a prolonged exposure to colourant particle found to cause an unacceptable discolouration of microhybrid composite resin.