There is substantial evidence from preclinical data that the antitumor cytotoxicity of selected chemotherapeutic agents either alone or combined with radiation can be enhanced by appropriate heat exposure (40-44 degrees C) of cells or tumor tissues. Based upon these results the integration of hyperthermia as an additional treatment modality, given simultaneously with systemic chemotherapy or in combination with radiochemotherapy, is currently tested at the clinic. Regional hyperthermia combined with chemotherapy or radiochemotherapy showed impressive results (phase II studies) at clinical relevant temperatures in locally advanced tumors of different entities in terms of objective response rate, local tumor control and relapse-free survival. Clinical protocols of well-designed phase III trials on combined treatment modalities integrating hyperthermia are rather limited but for some tumors confirm its clinical benefit. In general, the clinical approach to use hyperthermia has gained much more interest within in the field of medical oncology. One of the major reason is the substantial technical improvements made with the available commercial equipment for local or regional heating, especially in case of deep-seated lesions or systemic heating. Further testing of the potential of hyperthermia combined with chemotherapy or radiochemotherapy in prospective randomized trials are warranted. At this time, hyperthermia as an adjunct to conventional treatment strategies is recommended in the setting of clinical protocols. The results of prospective trials should answer the question for which types of local advanced or metastatic tumors hyperthermia becomes standard as part of a multi-modal treatment strategy.