In this study, the floristic composition of the vegetation types of Sivrihisar Mountains (Sivrihisar/Eskişehir) were investigated. In order to determine the vegetation of region, a total of 1100 plant specimens collected in the vegetation period between March 2003-September 2005. As a result of evaluating these samples, 184 genera and 337 taxa that belonging to 49 family have been identified. In this study, taxa, specific to vegetation types of the research area, are given.In this study, the floristic composition of the vegetation types of Sivrihisar Mountains (Sivrihisar/Eskişehir) were investigated. In order to determine the vegetation of region, a total of 1100 plant specimens collected in the vegetation period between March 2003-September 2005. As a result of evaluating these samples, 184 genera and 337 taxa that belonging to 49 family have been identified. In this study, taxa, specific to vegetation types of the research area, are given.