Oral mucositis is one of the most common effects of chemoradiotherapy in patients with oropharyngeal cancer. The development of oral mucositis is the main cause of interruption of antitumor therapy, which significantly affects the results of treatment of the main disease. Despite the fact that the disease is well studied in the literature, today there is no universal treatment and prevention protocol. The aim of this review is to analyze scientific publications devoted to the problems of etiology, pathogenesis, clinic, diagnosis, treatment and prevention of oral mucositis.