It has been unequivocally demonstrated that hyperthermia (40-44 degrees C) has an potentiating effect on radiotherapy and chemotherapy. Technical improvements have facilitated the application of both local and whole-body hyperthermia, and have thus made this form of treatment available to large numbers of patients. Randomized phase III studies performed in patients with breast cancer, malignant melanoma and cervical cancer have convincingly confirmed the increased efficacy of the combination of radiotherapy with local or regional hyperthermia in comparison with radiotherapy alone. The effectiveness of other procedures such as the combination of radio- and chemotherapy with regional hyperthermia, regional thermochemotherapy and whole-body hyperthermia has so far been investigated mainly in phase II studies focusing on head and neck cancer, cervical and ovarian cancer, sarcoma, malignant germ cell tumors, and rectal carcinoma. However, the actual place of hyperthermia as a permanent element in a multimodal therapeutic concept has yet to be shown in prospective phase III studies.