This study examined a possibility of dextran magnetite (DM)-incorporated thermosensitive liposomes, namely thermosensitive magnetoliposomes (TMs), as a new hyperthermic agent. The temperatures of TM suspensions and cancer tumors injected with TM suspensions were efficiently elevated up to 42 degrees C by electromagnetic induced heating at a frequency of 500 kHz under both in vitro and in vivo conditions. Thus, a possibility of TMs for selective hyperthermia was demonstrated. The temperature rises obtained at various concentrations of TMs suggest that approximately 15 mg Fe/cm3 tumor volume is adequate as a therapeutic dose of TMs for efficient selective hyperthermia.