This study was conducted to evaluate the effect of royal jelly on oral mucositis in patients undergoing radiotherapy and chemotherapy. The study population consisted of 103 patients undergoing radiotherapy and chemotherapy. Oral mucositis was graded according to the World Health Organization criteria, and patients were divided into 2 groups. All patients received mouthwash therapy with benzydamine hydrochloride and nystatin rinses. In addition, patients in the experimental group received royal jelly. The mean resolution time of oral mucositis in the royal jelly group was significantly shorter than that of the control group. As a result, the study results demonstrate that royal jelly administrated by a certain procedure improved the signs and symptoms of oral mucositis and markedly shortened its healing time.