Of the 49 patients with squamous cell carcinoma of the buccal mucosa referred to the Rotterdam Radio-Therapeutic Institute (RRTI) and Universital Hospital Dijkzigt Rotterdam (AZD) during 1970-1984, 31 patients had an advanced stage of disease, 21 patients had clinical evidence of lymph node metastasis. Forty patients were treated with curative intention. Treatment modalities were: radiation therapy, preoperative radiation followed by surgery, and primary surgery. Eighteen of the 40 patients (45%) developed a local tumor recurrence; nearly all recurrences occurred within 2 years. The incidence was equal in all treatment groups. Of the 22 patients with initial clinically negative neck, regional relapse occurred in 3 of the 14 patients, of whom the neck was not treated electively by radiation therapy; all three in combination with a local recurrence. None of the 8 patients with electively irradiated necks developed a regional relapse. Eight of the 18 patients with initial clinically enlarged lymph nodes treated either by radiotherapy or surgery, developed a regional relapse, 5 in combination with a local recurrence. Treatment of the clinically positive neck by neck dissection was superior to radiotherapy. Local recurrence carried a poor prognosis. Almost 70% died of their disease. The overall and corrected 5-year survival was 38% and 52% respectively.