To clarify the role of thermoradiotherapy for FIGO Stage IIIB cervical carcinomas, both the clinical response and survival of patients treated with radio- or thermoradiotherapy were investigated. Forty patients with Stage IIIB uterine cervix carcinoma were treated with external beam irradiation to the pelvis, combined with iridium 192 high-dose-rate intracavitary brachytherapy. All patients were divided randomly into the following two groups: the radiotherapy (RT) group of 20 patients, who underwent radiotherapy alone; and the thermoradiotherapy (TRT) group of 20 patients, who underwent three sessions of hyperthermia in addition to radiotherapy. The primary endpoint of this study was local complete response and survival. A complete response was achieved in 50% (10 of 20) in the RT group versus 80% (16 of 20) in the TRT group (p = 0.048). The 3-year overall survival and disease-free survival of the patients who were treated with TRT (58.2 and 63.6%) were better than those of the patients treated with RT (48.1 and 45%), but these differences were not significant. The 3-year local relapse-free survival of the patients who were treated with TRT (79.7%) was significantly better than that of the patients treated with RT (48.5%) (p = 0.048). TRT, as delivered in this trial, was well tolerated and did not significantly add to either the relevant clinical acute or long-term toxicity over radiation alone. TRT resulted in a better treatment response and 3-year local relapse-free survival rate than RT for patients with FIGO Stage IIIB cervical carcinoma.