Purpose: The radioprotectors currently available are generally poorly tolerated in human beings; thus, their use has been restricted due to their side effects and their limited clinical tolerance. In a search for fewerand/or without side effects agents, the radioprotective effects of partial body hyperthermia (PBH) were tested on Wistar rats of both sexes at different ages. Materials and methods: PBH (43 °C, 1 h) was carried out by immersion of each animal’s lower parts and legs in a thermostatically controlled water bath 20 h prior to irradiation with a lethal single exposure dose of 9 Gy of gamma irradiation. Irradiated PBH pretreated animals were monitored for 30 days post-irradiation and survival percentages were calculated. Results: The data obtained provide evidence that PBH treatment prolonged the irradiated rats’ lifespans and the mortality rates varied significantly with animal age and sex. In addition, PBH treatment significantly enhanced bone marrow recovery of irradiated rats of both genders. Conclusions: Partial body hyperthermia prior to radiation proved to have beneficial effects on gamma irradiated rats.