A 59-year-old woman was admitted to our hospital because of massive bleeding from a right breast tumor. The breast tumor had existed for ten years occupied the entire right breast (23 x 20 cm), its central part forming an ulcer 17 x 15 cm in size. Radiotherapy to the right breast and medication with tamoxifen were started, after which five courses of CMF chemotherapy were given. The tumor decreased to 16 x 14 cm, and hyperthermia to the right breast was performed for a total of 87 sessions from January 1999. The irregular protruding portion of the ulcer caused the necrosis, and was sloughed off about one month after hyperthermia. No viable tumor cells were observed in a biopsy taken at 5 months after the start of treatment (40 sessions). A total of 87 hyperthermia sessions were performed, and the ulcer disappeared. For 15 months after the end of hyperthermia, the patient showed a continuous CR. Hyperthermia in combination with radiotherapy or chemotherapy for breast cancer may produce a remarkable effect as in the present case, and may become one choice for medical treatment of locally advanced or recurrent breast cancer.