Method and apparatus to automatically monitor and control a perfusion hyperthermia treatment using a system including one or more programmed computers, and mechanical and sensor subsystems. The system includes a fluid path between a patient and an external fluid-treatment subsystem, wherein control of the external fluid-treatment subsystem includes feedback from sensors coupled to the patient. The resulting integrated system provides automated monitoring and control of the patient, the external fluid-treatment subsystem, and the treatment. In one embodiment, the fluid passing between the patient and the external fluid-treatment subsystem is blood. In one embodiment, an apparatus and method are provided for using a computerized system for a perfusion hyper/hypothermia treatment of a patient which obtains a body fluid having a temperature. A plurality of temperature signals representative of temperatures at each of a plurality of patient locations on or within the patient are coupled to the computer system. Measured temperatures are compared to a set of stored parameters in the computer system to generate a comparison value which controls a change in the temperature of the body fluid. The body fluid is then perfused into the patient to either warm, cool, or maintain the current temperature of the patient. In one such embodiment, the body fluid is blood withdrawn from the patient. In another such embodiment, the body fluid is saline.