(1) Objectives: Lamotrigine, a new antiepileptic drug, has analgesic properties in its antisodium and antiglutamatergic effects. It may prevent postoperative pain. The purpose of this study was to evaluate the ability of oral Lamotrigin for postoperative pain reduction in impacted third molar surgery. (2) Design: This is a double-blind randomised clinical trial study, that evaluate the effect of oral Lamotrigine on postoperative pain reduction in patients requiring impacted third molar surgery whom will be reffered to school of dentistry of shiraz medical sciences. The following parameters such as: Individual patient information, medical history, the patient's hemodynamic values before- during and after surgery, duration of operation will be recorded. Severity of pain was evaluated by visual analoug scale (VAS) (100-mm) and the amount of analgesic consumption after surgery, was recorded in maxillofacial ward. pain was measured after patient transfered to recovery room. After surgery, the pain was assessed on a visual analogue scale (VAS) at intervals of 1/2 hr at rest. Total analgesic consumption in the first 12hr after surgery was also recorded. (3) Setting and conduct: A total of 50 adult patients were selected for this randomized controlled trial. All subjects were divided into two groups to receive Lamortigine or placebo. While anesthesiologist, and student project manager would be unaware of an intravenous drugs. ( Medications taken by nurses are randomly coded ). An informed consent approved by the Ethics Committee of the Shiraz University of Medical Sciences. The anesthesiologist administered 200 mg of lamotrigine orally with 20 cc water in study group and in the control group patients received placebo. Blood pressure and heart rate will be monitored, postoperative pain and necessity for postoperative analgesic immediately after surgery, in the recovery room and until 4 hours after operation will be calculated and recorded. (4) Participants including major eligibility criteria: Inclusion criteria included 15-25 year old patients whom were scheduled to undergo impacted third molarl surgery؛ Subjects who had systemic disease and history of drug consumption, history of drug allergic reaction, hepatic and renal dysfunction and lack of signed informed consent will be excluded from the study sample . (5) Intervention: Patients in the study group will be received an 200 mg Lamotrigine orally 1 hr. befor surgery and the placebo group will receive placebo as same route of administration. (6) main outcome measures: Primary outcome measure was evaluating pain intensity over 16 hours after surgery. Secondary efficacy measures included analgesic consumption and safety and tolerability of lamotrigine. During surgery heart rate, blood pressure and blood oxygen saturation is recorded at specified intervals and at the end of the operation analgesics usage were recorded. After surgery the patients were monitored for up to 4 hours in the recovery room and pain intensity (VAS 100-mm) is measured by a person who was uninformed about case and control groups every half hour. Pain relief drug consumption for patients will be recorded up to 12 hours in home by telephone. post-operative complications will be asked in the questionnaire. Patient's satisfaction was evaluated as poor (0), moderate (1), good (2), and excellent (3).