This randomized double blind Clinical trial study was accomplished to compare the analgesic effect of Celecoxib 200mgand Gelofen 400 mg on post endodontic pain. Ninety patients in 3 groups (30 patients in each group) recruited. In a double blind study, capsules of Celecoxib, Gelofen and Placebo were randomly prescribed to the patients 1 hour before treatment. Patient reported visual analog Scale rating of pain intensity, were used upon initial clinical presentation and patients were asked to record their pain at 4, 8, 12, 24 and 48 hours after intervention. Inclusion criteria were: age between 18 to 65; and having vital premolars of mandible or maxilla without any pre apical lesion and exclusion criteria were: pregnancy; allergy to sulfonamide and NSAIDs; history of asthma related to nasal polyp; history of chronic using of analgesics; alcohol using; uncontrollable high blood pressure; diabetes mellitus; systemic disease and not using analgesic medicine 12 hours before study. Primary outcome of the study was the pain after surgery and measured by pain visual analogous scale.