The purpose of this study is to evaluate and compare the quality of the plans made with IRIS collimator and MLC for intracran ial treatments performed with Cyberknife. Homogeneity, conformality, gradient index, Monitor Unit and treatment time parameters were used in the evalu- ation. When creating treatment plans, attention was paid to the fact that % 100 of the prescribed dose enveloped % 95 of the target volume, while ensuring maximum protection of critical organs. Treatment plans were made for the target volumes of 10 cases with brain metastases in different localizations using two different collimators. The dose prescribed in the plans was defined as 18 Gy in 3 fracti ons. In order to make an accurate comparison, the planning parameters used for IRIS collimator and MLC were kept constant for each case. The prescribed dose was defined as a minimum isodose curve of % 80. There was no statistically significant difference between the two decoup les for the values of HI, nCI, GI (p>0.05). CI was lower in plans with IRIS than MLC, and for MU and MLC treatment periods, quite low values were obtained in plans with IRIS collimator and there is a statistically significant difference (p<0.05). The mean MU values were 10399 ± 3017.3 MU, 3166 MU ± 792.7 MU for IRIS and MLC, respectively, and the mean treatment time was 25 ± 7.5 min, 14.5 ± 2.3 for IRIS andMLC, respectively. When the quality of the plan for IRIS collimator and MLC was compared in the treatment of intracranial Cyber knife, it was found that in the plans made with MLC for the duration of treatment and MU, the treatment was completed in a shorter time wit h less MU value without loss in the quality indices. This, in turn, allows the patient to complete his treatment in less time.