Physicians, biologists and physicists present their recent work in the field of hyperthermia with regard to both its application and its combination with radiation and chemotherapy. Current technical possibilities, clinical management and major aspects of its use for superficial and deep-seated tumors are pointed out. The main topics discussed are: changes of metabolism and microcirculation under heat conditions, the biological interaction of heat with X-rays and several chemotherapeutic agents, and the most recent clinical data from different institutions on the combined application in the treatment of cancer.