From 1970 to 1986, 117 patients with T1 (47) or T2 (70) epidermoid carcinomas of the floor of the mouth (SCC) were treated by iridium-192 implantation (192 Ir). The dose was prescribed according to the Paris System and varied over those years. Follow-up information was available on 116 patients. There were 46 T1N0, 47 T2N0, and 23 T2N1-3. Neck management varied for the 93 N0 patients consisting of surveillance (24 T1, 17 T2) or elective neck dissection (22 T1:all pN-, 30 T2: 20 pN-, 10 pN+). Cause specific survival rates were 94% for T1N0, 61.5% for T2N0, and 28% for T2N1-3 at 5 years. Primary local control was 93.5%, 74.5%, and 65%, respectively, and 98%, 79%, and 65% after salvage. Patients with gingival extension or a tumor size over 3 cm (T2b) had a local control of 50% (9/18) and 58% (15/26), respectively. Nodal control was 93.5% for Stage I, 85% for Stage II, and 48% for T2N1-3 patients. There was no difference in nodal control with regard to treatment policy for Stage I-II patients. There were few complications including three deaths: two from surgery and one from 192 Ir. Nodal status, tumor size defined as T1, T2a (less than or equal to 3 cm), T2b (greater than 3 cm), and gingival extension were the only independent prognostic factors. The management of T1N0 and T2N0 SCC by 192 Ir to a dose of 65 or 70 Gy, using the Paris System, is recommended for lesions 3 cm or less and without gingival extension.