The purpose of this study was to evaluate the use of a preoperative, single oral dose of Prednisolone in controlling postendodontic pain after single visit treatment of acute irreversible pulpitis in a randomized controlled trial. Materials and methods; Forty patients suffering acute irreversible pulpitis in molars were randomly assigned into two equal groups with 20 patients per each, according to premedication Prednisolone (40 mg) and Placebo groups. The medications were administered 30 minutes before the start of standard endodontic treatment and Placebo with a green color was given as post treatment analgesic. Postoperative pain was assessed after 6, 12, and 24 hours by using a Visual Analogue Scale. Result; Results showed that Prednisolone made a statistically significant reduction in postendodontic pain at 6, 12, 24 hours when compared to Placebo. The Prednisolone group sowed statistically significant change in Visual Analogue Scale score through different intervals. In Placebo group there was only a significant decrease in VAS score from 12 to 24 hours. conclusion; Administration of a single preoperative oral dose of Prednisolone (40 mg) 30 minutes before start of treatment was effective in controlling post endodontic pain at 6,12,24 hours post operatively.