The authors describe the theoretical principles and the experimental and clinical investigations that form the basis for the technique of selective hyperthermic perfusion of the limbs, with or without the addition of antiblastic agents. Neoplastic cells are much more sensitive to heat than normal cells, undergoing necrosis at a temperature of 42.5 to 43 degrees C. The authors discuss the histological appearances and the clinical results obtained in the treatment of 29 cases of malignant neoplasms of the limbs in which antiblastic hyperthermic perfusion was carried out one month before surgical removal of the neoplasm. The long term results show that antiblastic hyperthermic perfusion significantly reduces the risk of local recurrences in cases of resection and in some cases enables amputations rather than disarticulations to be performed. This type of treatment is particularly indicated in the highly undifferentiated and aggressive forms such as osteosarcoma, malignant fibrous histiocytoma, adamantinoma, fibrosarcoma, giant-cell sarcoma, Ewing's tumour, and synovioma.