To evaluate the effect of surface sealants containing different filler content on the color stability of microhybrid and nanofilled composite resins.The materials evaluated as study groups were comprised a nanofilled composite resin (Filtek Ultimate, 3M ESPE) and a microhybrid composite resin (Filtek Z250, 3M ESPE). Forty-five disc-shaped specimens (10 mm × 2 mm) were prepared from each composite resin. Each study group was divided into three subgroups: control, G-Coat Plus, and Fortify Plus ( = 15). The baseline color values (***) of each specimen were measured using a spectrophotometer according to the CIE *** color scale. Then, the specimens were immersed in red wine for a period of 3 hours per day for 15 days (3 hours/day × 15 days). After the immersion period, the color values (***) of each specimen were measured again. The Δ*, Δ*, and Δ* values and the color change value (Δ) were calculated. The data were statistically analyzed with two-way ANOVA and Duncan tests ( = 0.05).All the composite resin groups demonstrated/indicated much more color changes after immersion in red wine (Δ > 3.3). The greater Δ values were observed with the groups applied surface sealants than the control groups ( < 0.05). Fortify Plus further increased the Δ values of both composite resins than G Coat Plus ( < 0.05). Filtek Ultimate showed higher Δ values than Filtek Z250 in all the subgroups ( < 0.05).The surface sealants regardless of the filler content negatively influenced the color change of the composite resins after immersed in red wine. The microhybrid composite resin had better color stability than the nanofilled composite resin.There is no favorable effect of using surface sealants on composite resins to prevent discoloration; besides, the sealants can also increase the color alteration.