Radiotherapy aims to cure or shrink early-stage cancer, lower recurrence rate, treat symptoms caused by cancer and treat cancer recurrences. The three main ways of administering radiotherapy are internal, external or systemic. Since radiotherapy can improve both clinical and functional outcomes, it is used in the majority of head and neck cancers. Tumours of the paranasal sinuses generally require complete surgical resection; however, radiotherapy can still be used for tumours with positive or close surgical margins as well as locally advanced tumours (Yeh, Semin Plastic Surg 24:127–136, 2010). For unresectable tumours, radiotherapy can be combined with chemotherapy as a definitive treatment.