The aim of the present study was to evaluate the effect of staining agents(coffee, soft cola drink, lipstick with common fixer, lipstick with ultrafixer) and repolishing on the color stability of Nanofilled andMicrohybride resin composite.Materials and Methods: A total of one hundred bovine incisors was used in this is study ,labial cavity with similar dimension was done on the bovine incisors ,then the incisors was divided into two equal group(n=50) ,one group wasrestored with nano-filled composite (Composan bio- esthetic,PROMEDICA, Neumunster/Germany shade A1 ) resin and the othergroup was restored with micro-hybrid glass-ceramic micro-hybridcomposite resin ( composan ceram ,PROMEDICA, Neumunster/Germanyshade A1) composite resin , after finishing and polishing of therestoration the baseline color of the restoration was measured beforeexposure to the staining agent.Each group was further subdivided into five subgroups (n=10)according to the type of staining agent:G1-distall water(control) , G2-coffee , G3- cola soft drink , G4- lipstick with common fixer , G5-lipstickwith ultra fixer .the exposure time first was one hour then, the new colormeasurement was done. After that, the exposure time was 24 hour then,then the new color measurement was done .after word , the restorationwas repolished and submitted to new color reading.Color stability was determined by the difference in the color readingbefore and after exposure to the staining agent and after repolishing.The results: The results of the present study revealed that each of the threevariables (composite type, exposure time, staining agents) tested in thisstudy had an effect on the color change. Composan bio – esthetic showedmore color stability than composan-ceram. Concerning the discoloration,lipstick with ultra fixer( long-lasting lipstick) produced the highest colorchange followed by coffee, cola and lipstick with common fixer (creamylipstick )produce the same discoloration and coffee showed worserepolishing results compared to coca-cola or ultra-fixer and commonfixer lipstick.Conclusions: Color stability of the resin composite depends on the resin compositetype, exposure time, staining agent & Repolishing was found to be aneffective way to improve esthetic appearance for resin compositerestorations.