Clinical hyperthermia with controlled alteration of temperature (40 to 44 degrees C) in the target area is used in interdisciplinary treatment concepts for tumor treatment in combination with radiation and/or radiotherapy. Besides the direct cytotoxic power of hyperthermia there is an immunomodulatory effect and a radiation and chemotherapy sensitizing effect in the heated tissue. Clinical hyperthermia is an invasive or non-invasive supply of energy to the body of the patient, which leads to an artificial heating of the tumor and the surrounded tissue. The clinical hyperthermic procedures should take into account the oncologic disease and its pattern of organ involvement. There are three different types of hyperthermia: local hyperthermia (LHT), regional hyperthermia (RHT) and part body hyperthermia (PBH). PBH is used to heat regions of the body in case of metastatic disease, e. g. to the abdomen. I and phase II trials could show that the effects of radiation and chemotherapy can be altered by the simultaneous addition of hyperthermia. Data of trials involving skin metastasis in malignant melanoma, local relapse in breast cancer, tumors of the head and neck with regional lymph node metastasis, as well as trials in colorectal tumors, bladder cancer, pancreatic cancer, cervical cancer and sarcoma are presented. The results shows, that response to treatment can be improved by hyperthermia.