Between October 1964 and December 1983, 48 patients with malignant tumors of the nasal cavity (31), ethmoid sinus (13), or sphenoid sinus (4) were treated with curative intent by radiation therapy. There were 21 squamous cell carcinomas, 14 minor salivary gland tumors (adenocarcinoma, adenoid cystic carcinoma, and mucoepidermoid carcinoma), 3 malignant melanomas, 2 soft tissue sarcomas, and 8 esthesioneuroblastomas. Forty-two patients were treated with irradiation alone and six with planned combined irradiation and surgery. The 10-year actuarial local control rate for Stage I (limited to site of origin; 7 patients) was 100%; for Stage II (extension to adjacent sites, e.g., adjacent sinuses, orbit, pterygomaxillary fossa, nasopharynx; 19 patients) was 53%; and for Stage III (destruction of skull base or pterygoid plates, or intracranial extension; 22 patients) was 30%. Of 24 failures at the primary site, 10 occurred greater than 24 months after completion of irradiation. With the exception of adenoid cystic carcinoma (17% local control at 15 years), the ultimate local control rates for all histologies were in the range of 40% to 60%. Of 7 patients with documented intracranial extension, 3 (43%) remained free from local recurrence 3.5, 4, and 9 years after treatment. The 5-, 10-, 15-, and 20-year uncorrected actuarial survival rates for all 48 patients were 52%, 30%, 22%, and 22%, respectively. Continuous disease-free survival according to stage at 10 years was 86% for Stage I, 42% for Stage II, and 22% for Stage III. The single failure in a patient with Stage I disease was a lymph node metastasis that was successfully managed by radical neck dissection. The orbit was grossly invaded by tumor prior to treatment in 22 patients (46%). Sixteen (33%) of 48 patients developed unilateral blindness secondary to radiation retinopathy or optic neuropathy; in the majority of these patients the complication was anticipated because the ipsilateral eye was irradiated to a high dose. Four patients (8%) unexpectedly developed bilateral blindness 17, 35, 46, and 90 months following treatment owing to optic nerve injury. A discussion of possible means of avoiding this latter, unacceptable complication is included.