C Composite resins have the ability to absorb fluid that allows the absorption of moisture in the oral cavity that will lead to a discoloration in dense material. One of the extrinsic factors that influence discoloration in the composite resin is the used of mouthwash. This study is conducted to determine the discoloration that occurs in the composite resin due to the influence of mouthwash. The composite resin that used in the study is the type of the composite resin called microhybrid. The 16 research samples are divided into two treatment groups. The first group is soaked in water as a control sample and the second group is soaked in mouthwash. Samples are soaked for 72 hours. The first observation is observed by looking at the change of r, g, b color on the clinical picture before and after the submersion using the Adobe Photoshop CS3 program. The observation states that there are changes in the value of r, g, b which get lower and lower on the clinical picture after soaking it in the mouthwash; which means the discoloration happens and the color becomes increasingly darker. The statistical test on r indicates p <0.05 and F> F crit which means there is a significant difference for r before and after the submersion. For g and b show p> 0.05 and F 0.05 and F