An analysis has been undertaken of 45 patients with non-metastatic squamous cell carcinoma of the buccal mucosa treated by permanent 198Au or 222Rn implants and in most cases supplementary external irradiation. Eight patients had T1, 30 had T2, and 7 T3 disease. Of the lesions 21 were located in the buccal mucosal surface, 14 in the retromolar region, and 10 in the bucco-alveolar sulci. Seven of the 45 (16%) died of the disease and the actuarial 5-year survival rate was 81%. No obvious differences were noted in survival rate between different stages of the disease or between different subsites of the primary lesion. There were 6 local recurrences occurring from 3 to 33 months after treatment, and only one of these was salvageable by further radiation therapy. Neck node metastasis occurred in 11 cases from 2 to 34 months after treatment, and 8 of these cases responded successfully to a radical neck dissection or radiotherapy.