The aim of this in vitro study was to evaluate the sorption (Sp) and solubility (Sl) of a nanofilled composite (Filtek™ Z350) light-activated from the top in three curing light distances (0 mm, 3 mm and 6 mm) and immersed in three different mouthwashes (Plax Fresh Mint, Plax Alcohol Free, and Plax Whitening). Specimens (6 mm Ř and 1 mm height) were prepared (n = 5) and initially the degree of conversion (DC%) of discs was obtained by using a fourier transform infrared spectrometer. Then, the specimens were placed in a desiccator at 37°C and were weighed until a constant mass (m1) was obtained. The discs were immersed in the mouthwashes for 30 days. Twice a day, the samples were immersed in 2 ml of the mouthwashes (12 hr intervals). After the 30-day period, the discs were reweighed (m2). The reconditioning in the desiccator was done until a constant mass (m3) was obtained. The data of DC% were analyzed by analysis of variance (ANOVA) in split plots and the results showed statistical difference when photoactivated to 6 mm from the tip of the curing unit. The sorption data were submitted to two-way ANOVA and Tukey’s Test at a 5% level of significance and it was observed that a statistical difference (P < 0.05) was only cured when the distance was 6 mm, but there was no difference in sorption between mouthwashes. The solubility data were analyzed by Kruskal-Wallis’s Test (P = 0.05) and Dunn’s Test, since a non-normal data distribution was observed. The values were negative, which means that there was a mass gain, masking the real solubility.