We report on a 69-year-old woman with rhabdomyosarcoma arising from the nasal and paranasal sinuses. She was referred to our hospital with a reduced ability to smell and impaired bilateral vision, narrowing of the visual field, and left facial pain. Computed tomography (CT) revealed a large tumor in the nasal and left paranasal sinuses invading the left orbital cavity and anterior skull base, and lymph node swellings in the submental and left accessory nerve areas. A biopsy specimen from the nasal tumor was diagnosed histologically as a rhabdomyosarcoma, alveolar type. Because the intracranial direct invasion and distant metastases to the thoracic spine were suspected by pretreatment examination, our case was determined to be inoperable by a head and neck surgeon. Radiotherapy with a total dose of 60 Gy was carried out to control the primary disease. The three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) techniques were used in order to reduce the doses to risk organs. Combined with radiotherapy, chemotherapy was also performed for the treatment of lymph-node metastases and distant diseases. After the treatment was completed, the primary tumor and lymph-node metastases disappeared completely; there was no sign of re-growth during the follow-up period. Chemoradiotherapy may be an effective treatment also for inoperable adult rhabdomyosarcoma in the head and neck region. Furthermore, the 3D-CRT and IMRT techniques are both useful methods of radiotherapy for this disease.