Hybrid composites were prepared by adding one or two plies of polyethylene (PE) fabric to the bottom side of four-ply carbon fiber/vinylester composites. The effect of the surface treatment of PE fiber on the impact properties of carbon fiber/PE fiber hybrid composites was investigated using oxygen plasma, y-MPS, and y-MPSmodified polybutadiene (PB/y-MPS) as surface modifiers. Carbon fiber/vinylester composite exhibited brittle failure with cross-shaped crack at the back side. The addition of PE fabric on the bottom side resulted in a change of the impact behavior of hybrid composites. After hybridization, the absorption of much impact energy was attributed to a considerable degree of plastic deformation in PE plies and the delamination at the interface between carbon and PE layer, However, the surface treatment of PE fiber reduced the impact energy of composites with restriction of deformation at the interface between the carbon and the PE layer. Moreover, the addition of a treated PE layer decreased the degree of deformation with a daggershaped deformation zone at the back side. The extent of the deformation area had a significant effect on the impact energy of the hybrid composites.