Reinforced polymer composite materials have opened a new era because they can substitute the conventional metallic materials. These materials have found numerous usage areas, especially in aviation, military and space applications due to such advantages as the high tensile strength, high modulus, high corrosion resistance and low density. However, during the assembly of parts from these materials, a huge amount of holes is required. There are problems during machining of reinforced polymer composite materials. Main reason behind these problems is the inhomogeneous microstructure. Some of these problems are burr, pullout, swelling, microcrack, rapid tool wear and delamination. Among the most important of these defects is the delamination damage. Delamination is a severe drilling failure. In this work, three different cutting speeds (15, 20, 25 m/min), three different feed rates (0.05, 0.10, 0.15 mm/rev) and three different cutting tool materials (Carbide, TiN Coated HSS and HSS) have been used. Effect of different feed rates, cutting speeds and tool materials on delamination is studied by drilling of % 10 glass sphere- and % 10 silicon particle-reinforced polypropylene hybrid composite material.