The study evaluated the effect of different surface treatments on the surface roughness of a new-generation fiber-reinforced CAD-CAM composite resin (FRC) and its bond strength to veneered composite resin. Fifty specimens (10 mm x 10 mm x 1 mm) were prepared from FRC blocks (Trinia; Shofu) and embedded in acrylic resin. The specimens were divided into five groups (n = 10) for different surface treatments: nontreated (control), Al2O3 airborne particle abrasion, silica coating (Cojet), acid etching (H2SO4) and hydrogen peroxide (H2O2) application. Surface roughness (R-a) of the specimens was measured using a profilometer. A veneering composite resin (3 mm in diameter by 4 mm in length) was applied on the specimens. The shear bond strength between the FRC and the veneering resin was measured. A one-way analysis of variance was used to analyze the data. The differences among the groups were analyzed with Dunn post hoc tests (alpha = 0.05). Surface treatments increased the surface roughness, and Al2O3 airborne particle abrasion resulted in the highest R-a value followed by H2SO4, Cojet, H2O2 and control group (P < 0.05). The highest shear bond strength was achieved with Al2O3 application (P < 0.05). Cojet and H2O2 applications resulted in higher shear bond strength than the control (P < 0.05). H2SO4 application resulted in lower bond strength than the control (P < 0.05). Surface treatments increased the surface roughness of FRC. Al2O3 and silica coating increased the surface roughness more than the chemical applications. The tested surface treatments can be used to increase the bond strength except for the H2SO4 application. (c) 2021 Society of Chemical Industry