An evaluation of the end results of combined treatment for osteogenic sarcoma by standard chemoradiotherapy (n = 66) and novel thermochemical therapy (n = 108) using local ultrasound hyperthermia (total number--174) demonstrated their dependence on the temperature range in target tumor tissues. Use of subhypertemperatures of 39--41-45 deg.C (TTD--36 Gy) did not improve the results of treatment. However, 41-45 deg.C (TTD--36 Gy) was followed by a significant increase in 3- and 5-year survival and improved quality of life in cured patients as compared with those receiving standard radiotherapy (TTD--60-110 Gy). Hyperthermic therapeutic effect in osteogenic sarcoma depends on certain conditions. Effective temperatures can generally be reached in patients with relatively large-size tumors and rather thin coats of subcutaneous fat.