The purpose of this study was to evaluate the effects of different growth pattern and treatment type factors on craniofacial structures in cases treated with fixed mechanics and premolar extractions, A total of 41 cases with a mean chronologic age of 14 years 7 months and skeletal age of 14 years 6 months was included in the study. These cases were treated with fixed Edgewise mechanics and with extraction of four first premolars. The growth pattern factor was assessed in two levels as mesiodivergent and hyperdivergent, and the treatment type factor was assessed as with and without headgear, The results were analyzed by two-way analysis of variance. In the assessment of differences between the two types of growth patterns at the end of treatment; the changes in N-ANS and N-M were found to be statistically significant (P <.05), In comparison of cases treated with and without headgear, changes in SNA and ANB angles were found to be statistically significant (P <.01). Interaction was found to be nonsignificant for all measurements. It was observed that treatment with fixed appliances and premolar extractions does not change significantly the growth pattern.