Delamination factor is an important parameter for evaluating the surface damage in the drilling of compact laminate composites (CLC). In this study, delamination occurred in the hole exit region was studied and the effects of control factors on delamination factor were investigated in the drilling of pre-drilled CLC materials with new (T1) and worn (T2) tungsten carbide flat end mill cutting tools. CLC workpieces are drilled on CNC machine at three different cutting speed (178, 250 and 350 m/min), three different feed rate (0.07, 0.111 and 0.156 mm/rev) and two different drilling type (linear drilling and peck drilling). An experimental study has been performed according to L18 (2(1)x3(2)) orthogonal array using Taguchi method and the optimum levels of control factors are determined. In addition, predictive equations were developed showing the effects of drilling parameters on delamination factor. Delamination factor calculated with an average of 1.036 in drilling T1 tools while delamination factor was measured with an average of 1.473 in drilling T2 tools. Analysis of variance (ANOVA) was applied to determine the effects of control factor on the delamination factor. The most influential parameters on delamination factor in drilling with T1 tools has been the cutting speed (65.30%), type of drilling (11.63%) and feed rate (8.16%) when the cutting speed (58.79%), drilling type (18.38%) and feed rate (3.43%) has been the most influential parameters on delamination factor in drilling with T2 tools, respectively. As a result; higher maximum deformed diameter was obtained in the drilling CLC material with worn tools.