A sensitivity analysis of the flood safety of Solaimantangeh dam using a regional climate change simulation is presented. Based on the output of the CCSM (Community Climate Change System Model) general circulation model, the NIRCM (North of Iran Regional Climate Model) computes regional scale output with 50 km spatial resolution and 21 vertical layers. Using the SRES (Special Report Emission Scenario) “B1” Climate Change Scenario when applied to the Tajan river basin, where Solaimantangeh dam is located, NIRCM reduces significantly the bias in Annual Maximum Event total Precipitation (AMEP) & Annual Maximum Daily Precipitation (AMDP) that CCSM shows. The stream flow change scenario is then simulated using SSARR (Stream flow Synthesis and Reservoir Regulation) model. A rainfall-runoff model was implemented using precipitation and temperature projected by CCSM and NIRCM. The model demonstrated that average Stream flow would increases 38.7% and the variability would increases 14.3%. This remarkable increase in projected annual maximum flow for the next 20 years (2004-2023) should be a significant negative signal to water resources managers. The results indicate that the number of floods remains almost the same, but that the magnitude of a single flood event and the recovery from it become worse.