Already at the beginning of the 19th century first clinical trials with systemically induced fever were performed on malignant tumors. An intensified research in thermobiology in the sixties of this century gave the rationale for using this modality for cancer treatment. Clinical use of hyperthermia in combination with radiation or chemotherapy begun in the mid of the seventies when a better technique for selective heating of the tumor was used. In the technical development the problem of heating deep-seated tumors was mainly solved. Temperature measurements of the tumor and surrounding tissues are performed with specialized thermometry systems using thin implanted catheters to measure inside the body. 1986 a pilot study was initiated at the Medical Clinic III of the Klinikum Grosshadern to study the effects of regional hyperthermia combined with systemic chemotherapy. This study is aimed on feasibility, toxicity, and tumor response.