The purpose of this study is to determine the effects of the instruction based on Van Hiele Model on preservice teachers' the geometrical thinking levels. This study has been carried out with senior students attending to the Elementary School Teaching Program. There were eight classes of senior preservice teachers, two of them were randomly assigned as experimental groups which were instructed with Van Hiele Model and the other two were randomly assigned as control groups which were instructed with traditional instruction. Based on the analysis of the data, findings will be discussed and some recommendations will be presented. (C) 2009 Elsevier Ltd. All rights reserved.