Aims and objective : To evaluate and compare the effect of coffee, chocolate drink and food dye on the color stability of conventional composite resin and nanocomposite resin. Design : The study sample consists of microhybrid composite and other nanocomposite of shade B1. 40 disks of each material with a diameter of 18 mm and thickness of 1 mm were prepared before discoloration procedure specimens were measured for L* a* b* values and then 10 specimens of each subgroup were immersed in each of three staining solution. The 10 remaining specimens of each main group were immersed in control solution. Discoloration values were analyzed at baseline, 1 week and 4 weeks following immersion in staining solution. The color and color difference of each specimen were measured by spectrophotometer. L* a * b* values of each specimens were measured 3 times by placing each specimen on the measuring head. Resistance to staining effect is expressed in ΔE unit and was calculated from the mean ΔL* a* and Δb* values for each specimens with the following formula. Equation : ΔE* = [(ΔL*) 2 + (Δa*) + (Δb*) 2] ½. Result : Result of study showed that nanocomposite is more stain resistant and color change ΔE*. Conventional composite demonstrates unacceptable color change ΔE* more especially in specimens immersed in coffee. Conclusion : The result of this study indicated tested conventional composite resin was more susceptible to change in color in various media over an extended period of time as compared to nanocomposite.