The authors carried out a theoretical review about body temperature as a decisive vital sign to maintain homeostasis. Emphasis needs be placed on the importance of maintaining a constant temperature within a range of 36.8 degrees C +/- 0.4 degrees C. After a brief review about thermoregulation mechanisms and thermal behavior in living organisms, the authors emphasize human beings' property as a homeo-thermal entity with characteristics which enable him to maintain a relatively constant body temperature in spite of physiological variations which make this temperature fluctuate. Upon evaluation this constant, we distinguish between relative values for superficial and central temperatures, detailing those mechanisms which influence the production or loss of heat that intervene to regulate body temperature by means of physioiogical responses to old and heat. Finally, the authors describe the necessity to maintain boy temperature following Virginia Henderson's fourteen necessities scale, once the factors which could modify it are kno wn in order to comprehend the meaning of measurements and their subsequent interpretation which leads to distinct Nursing diagnoses directed towards achieving independence in resolving this necessity.