Considering the importance of an appropriate hemodynamic control in patients undergoing spinal fusion surgeries especially heart rate and blood pressure for improvement in surgical field , the necessity of findings drugs with the ability to control the above mentioned parameters has increased. Remifentanil is a short acting and potent opioid which has used in different surgeries for blood pressure and heart rate control. Dexmedtomidine as an alfa-2 agonist has been chosen in this study with this hypothesis that could have a reliable control in blood pressure and heart rate. The study has designed to perform in 50 patients candidated for spinal fusion surgery with ASA class I&II and age between 15-65 years who have signed the informed consent, who had not any heart, lung, kidney and coagulopathy diseases. After block randomization and with randomized number table usage they were grouped to receive either remifentanil infusion as 0.2 micro/Kg/Min or Dexmedtomidine infusion as 1 micro/Kg/hr. Hear rate, blood pressure, oxygen saturation will be measured before and after anesthesia induction, in 1,2 and 3 hours later, after extubation and up to 1 hour in recovery room.Blood loss, surgeon satisfaction from surgical field, anesthesia emergence and extubation time, sedation and pain score in recovery, discharge time and first analgesic requirement time up to 6 hours will also be measured in recovery. The results will be recorded in prepared questionnaire and will be evaluated later.