Abstract: An improved method and apparatus for safely and rapidly rewarming large quantities of frozen or refrigerated blood combines microwave, or radio frequency radiation, heating with a forced air system. Forced air is flowed over units of blood or tissue from those units that will absorb the most microwave energy, generally those units closest to the source of microwave energy, to those units that will absorb the least microwave energy, generally those units furthest from the source of microwave energy. The forced air initially thaws the closest units so that they begin to absorb significant microwave energy. The forced air, preferably chilled, then prevents overheating of those closest units by transferring heat to more distant units, beginning their thawing and contributing to their rewarming. The microwave energy source is turned off when the output temperature of the forced air reaches a preselected temperature and the flow of forced air continues until the output temperature stabilizes.