Polymer composites are widely used in various fields and industries. This study investigated milling of four different glass and carbon fiber reinforced plastics. First, feed force values were determined in the milling process conducted using tools with polycrystalline diamond inserts, with titanium nitride-coated cemented carbide inserts and with uncoated ground cemented carbide inserts. Machined surfaces were then examined for roughness. Using scanning microscopy (SEM), differences in the surface layer were also determined. Results showed that the lowest force values were obtained in milling of glass fiber reinforced plastics using tools with polycrystalline diamond inserts. The best machining results in terms of roughness were obtained after milling glass fiber reinforced plastics.