Sixty-seven patients with squamous cell carcinoma of the oral cavity were treated by implantation of radio-active iridium wire between 1977 and 1986. The results are presented in the hope of providing a comparison with those of primary surgical management. The crude 5-year survival rates were 61% for T1, 74% for T2, and 37% for T3 tumours. The major causes of death were uncontrolled tumour in the neck and intercurrent disease. Seven of 52 patients with T1 or T2 tumours (13%) developed local recurrence at the primary site; five were salvaged surgically, for an ultimate failure rate of 4%. The ultimate failure for a group of 15 T3 tumours was 47%. The only morbidity was a 31% incidence of soft tissue ulcers occurring during the first 18 months after treatment, none of which persisted. Elective external beam radiotherapy to the clinically negative neck significantly reduced the incidence of overt lymph node metastases.