Background: One of the concerns in using composite resins is color change. The aim of this study was to investigate the effect of preheating on color stability of composite resins when immersed in coffee and tea. Material and Methods: this experimental study included 60 composite disks. The samples were divided into 2 groups, one group prepared at room temperature and the other prepared at 68°C. After curing, the samples were placed in 37 °C distilled water for 24 hours. The color of the samples was measured (t0) using spectrophotometer according to CIE-L*a*b* system. The samples of each group were then divided into 3 subgroups and respectively immersed in distillated water, coffee and tea for 30 days and the final color (t1) was measured. The difference between the measured colors was calculated (∆E) and the results were analyzed using version 21.0 of SPSS software, Paired t-test, ANOVA, Tukey's test, and Dunnett t-test. Results: The preheated composites showed significantly lower staining in the coffee solution than the room temperature composites (p<0.0001). In contrast, no statistically significant difference was observed for the tea solution (p=0.317). The staining of the preheated composites in distillated water was higher than those in the room temperature, however, the difference was not significant (p=0.99). Conclusions: Within the limits of this study, preheating was effective to improve color stability of composite resin after long time immersion in coffee solution.