Temperature elevation for a few degrees (degrees C) increases significantly the cytotoxicity of several antineoplastic drugs under experimental conditions. An isolated elevation of the tumour temperature, which is possible since a few years, might be able to improve local tumour control without increasing the systemic toxicity. This study was performed to examine the feasibility of regional hyperthermia with systemic chemotherapy in pediatric patients. The special interests were the level of temperatures that could be achieved as well as the degree of toxicity and undesired side effects. Furthermore there was some hope to attain local tumour control in cases with very poor prognosis. 34 patients up to 18 years were treated in Munich and Essen until the end of 1992. 21 suffered of local relapse, in 11 cases it was the 2nd up to the 7th relapse. In another 11 cases the indication for the combined treatment was tumour progress or non-response to previous therapy. 33 patients were pretreated by aggressive chemotherapy, 20 patients had received radiotherapy before. In 28 cases the tumour was located in the pelvis. The heating device that we use is commercially available. It is based on external electromagnetic radiation which induces heat by absorption within the tissue. Since the temperature distribution inside the tumours is very heterogeneous thermometry is necessary which can only be performed invasively. For this sake we use closed tip catheters which are inserted into the tumour by puncture or surgically. The catheters remain in place for the whole treatment duration of several weeks. Chemotherapy was performed in treatment cycles (3.4/patient) mainly using etoposide, ifosfamide, and carboplatin.(ABSTRACT TRUNCATED AT 250 WORDS)