A lot of researches are focused on decreasing the weight of manufactured components and increasing their mechanical properties, or achieve additional unique properties. One of the results of their effort is a composite material. This kind of material consists of two phases – matrix and reinforcing phase. This unique combination of phases causes the superior properties of the composite material. However, since material properties of the matrix differ from the material properties of the reinforcing material, certain difficulties during machining are caused. Between those difficulties are included: delamination of the machined composite and reduced tool life. Those facts motivate other researches to investigate the machinability of the composite materials. There has been described a few possibilities on how to improve the machining process during machining of composite materials. For example, Seco Tools Company starts with developing a new shape of the cutting tools; DMG Mori Company has successfully implemented assistance of the ultrasound into milling process and therefore achieved enhanced machinability od the materials; the scientists from the Stan-ford University have developed a diamond-like carbon (DLC) coating, which is available to satisfactory cut the reinforcing fibres as well as the soft matrix. In this article is compared ultrasonic-assisted face milling of the carbon fibre reinforced plastic (CFRP) and glass fibre reinforced plastic (GFRP) by a unique shaped milling cutter. There were observed delamination of those composite materials during mill-ing process via 3D digitization devices. The results of the research could be applied to determine how fibre material can affect ultrasonic assistance during the milling process. There were achieved lower delamination during machining of GFRP, however, lower surface roughness was achieved during machining of CFRP.