Thermoregulatory models of mature adults have been developed using the well established theory of hypothalmic temperature control about a set point. Experimental investigations have indicated that thermoregulation in newborn infants is different than that of mature adults. Thermoregulatory models require precise repeatable hypothalmic temperature data to which they can be compared and improved. The 0.1C or less oscillations of the hypothalmic temperature about its set point indicates the precision of temperature sensing and control in the human body. Measurement capabilities of 0.02C change in hypothalmic temperature are considered adequate to verify sophisticated adult models and to generate dependable data for development of newborn infant thermoregulatory control models. The purpose of this thesis is to document the precision of the prototype temperature telemetry system developed. This will be accomplished by exploring the physiological and experimental background of thermoregulation, describing the prototype device which was developed and finally by evaluating its performance as a method of precise physiological temperature measurement. / Master of Science