Abstract: Hospital patient temperatures are monitored by providing each patient with a battery powered transmitter containing a thermistor and reference resistor which is positioned over the patient's carotid artery. A receiver, carried by a nurse, includes an actuator for closing a reed switch in a transmitter near which it is positioned to activate that transmitter. Upon actuation of the transmitter, the patient's temperature varies the duty cycle of a high frequency transmitter output. The outputs of a number of transmitters, each associated with a different patient are elicited, one by one, and monitored by the receiver which contains a demodulator connected to a microprocessor coupled to a visual display. The microprocessor calculates patient temperature selectively in Fahrenheit and Centigrade conventions. The microprocessor also detects low battery condition in the transmitter. The receiver includes a self-calibration test and low battery indication circuits.