Drought is natural event which symbolizes the significant decrease in usage of water in wide field and specific time. Drought, which occurs in different areas of world, effects economical activities, human`s lives and different environmental factors. Complexity of global hydrological cycle obstructs finding the reason of drought. This study was intend to determine drought of the basin by using mean monthly straemflows in Seyhan basin in streamflow drouht index (SDI). In this reason, mean monthly streamflows gauge for 1967-2007 in flow station 1801-1818 number located on Seyhan river was used. According to SDI method 3, 6, 9,12 months in the index values were obtained expressing the drought severity. SDI values for each station in the 9-12-month reference period were obtained similar results. 3 and 6 months of drought values have gained importance after 2000.