The aim of this study is to evaluate the effect of whitening mouthwashes on translucency change (ΔTP) at different times of composite resins after coloring with coffee. In the study, a total of 90 samples (30 samples from each composite resin) were prepared from resin materials (Estelite Σ Quick, G-Aenial Anterior; Omnichroma). After kept in coffee for 12 days, the samples were divided into three subgroups (n=10). The initial (T0) measurement of TP values ​​were recorded. Control groups were kept in distilled water and the other groups were kept in two different mouthwashes (Listerine Advanced White, Crest 3D White). TP values ​​at the end of 24 hours (T1) and 72 hours (T2) were recorded. TP values ​​were determined using the CIEDE2000 formula. Two-way analysis of variance and Tukey test were used (p< 0.05). The lowest ΔTP value was observed in the control group at T0-T1 and T0-T2 times. The highest ΔTP value was observed in Crest 3D White mouthwash at T0-T2 time. However, there was no difference with Listerine Advance White. Among the composites, the highest ΔTP value was found in G-Aenial Anterior at T0-T2 time, and the lowest ΔTP value was found in Omnichroma at T0-T1 time. Whitening mouthwashes caused an increase in the translucency values of resin composites over time. It should be noted that long-term use of whitening mouthwashes may affect the translucency values of composite resins.