Abstract: A multi-stage system for warming blood that enables safe and rapid blood transfusions in the field. The first stage of the system is a rapid blood warming device that heats blood quickly from cold storage to body temperature. This stage may use a high-energy power source, such as AC power, that is available in a facility such as a hospital. The second stage is a portable heated blood transport device into which heated blood bags are placed for transportation to a patient. This device keeps the blood bags warm using battery power. Because blood bags are pre-heated with the rapid warming device, the transport device can be lightweight and portable. An optional third stage is a transfusion temperature regulating device that boosts the final temperature of blood just before it enters the patient. All three devices may have sensors and controllers that maintain blood temperature within desired ranges.