Meaningful evaluation of physiological changes resulting from microwave/radiofrequency radiation (MW/RFR) exposure depends upon accurate dose level determination. Comparison of experimental results from different investigators also requires firm establishment of dose levels. Review of the current literature reveals considerable inconsistency in this area. Therefore, a reliable method of specific absorption rate (SAR) determination in living animals must be established. In this article, we propose a new procedure for SAR determination which does not interfere with other complementary measurements required during experimentation. This simple and reliable method utilizes both the rate of temperature increase during irradiation and the rate of cooling following exposure. Current experiments suggest that the proposed method is an effective technique for local and whole-body SAR determination and allows an accurate evaluation of MW/RFR bio-effects.