Superselective intra-arterial chemoradiotherapy for head and neck cancer is a combination of intensive local delivery of anticancer drugs using microcatheters and external beam radiation. Unlike conventional chemoradiotherapy, it is highly effective in treating the primary tumor, but it cannot treat distant metastases. In the field of head and neck cancer, where quality of life is significantly impaired by curative surgery from a functional and cosmetic point of view, it is a useful treatment not only for unresectable cases but also for resectable advanced cancers, with the maxillary sinus being a particularly good indication. This treatment is expected to outperform conventional systemic chemotherapy and even comes close to the outcomes of radical surgery if the patient is carefully selected and the appropriate technique is used. Currently, a multicenter phase III clinical trial to evaluate the efficacy of this treatment for maxillary sinus cancer has been completed, and the results are being analyzed.