The aim of this study was to evaluate the influence of combined local anesthesia and low dose ketamine injection on postoperative pain, swelling and trismus following lower third molar surgeryMethodology:Thirty patients were selected in this study, their ages ranging from 18 to 30 years, they were randomly divided into two groups. All patients suffered from impacted lower third molar position B, mesio-angular or horizontal with almost the same degree of difficulty. One group were injected a 5ml combination of local anesthetic , ketamine and saline, the other group were injected a 5ml combination of local anesthetic and saline. Pain was measured by visual analogue scale. Swelling was measured using a horizontal and vertical measures with a flexible ruler following fixed anatomical points. Trismus was measured by Vernier caliper.Results and Conclusion:The use of ketamine significantly reduces postoperative swelling and pain following odontectomy of impacted mandibular third molar.