Gynecologic brachytherapy is a form of cancer treatment in which radioactive sources are placed into the pelvic organs via specialized applicators. Traditional low-dose-rate (LDR) brachytherapy has been performed over several days in a hospital setting. Since the 1990s, high-dose-rate (HDR) brachytherapy has been used increasingly because of its decreased treatment time, outpatient administration, and equal or superior efficacy compared with LDR treatment. However, the management of procedural pain in the radiation oncology setting has not been studied extensively. The purpose of this article is to discuss the use of oral transmucosal fentanyl citrate (OTFC) for the management of pain during gynecologic HDR brachytherapy. OTFC provides noninvasive, rapid analgesia with a low incidence of side effects and may be appropriate for other forms of procedure-related cancer pain.