[en] A group of 149 patients with carcinoma of the tongue or floor of mouth were treated with interstitial irradiation (+- external beam therapy) using cesium needles or iridium wires between 1970 and 1986. Multivariate analysis showed the main predictors of outcome to be tumor stage, site and histology. Cesium and iridium techniques gave similarly good local control rates of 90 percent at 5 years for T₁ and T₂ tumors when used as the standard departmental method. Local failure was shown to have a major impact on the risk of dying from disease and elective neck irradiation (ENI) conferred a favorable benefit on neck control and survival provided the primary site was controlled. Patients less than age 40 appeared to have an unfavourable prognosis. Radical irradiation including interstitial techniques gives excellent results in early oral cancer and is the treatment of choice for T₂ tumours. The authors recommend elective neck irradiation in patients at high risk of developing lymph node metastases. (author). 32 refs.; 3 figs.; 6 tabs