Abstract: An improved prediction-type medical thermometer that provides an accurate estimate of a patient's temperature in substantially reduced time as compared to prior thermometers of this kind. This improved performance is achieved by using a special hollow probe tip having a low heat capacity and incorporating a resistive heater that is actuated only upon removal of the probe from a base housing. The heater regulates the temperature to a value of about 93.degree. F. After the probe is applied to the patient, a microprocessor repeatedly samples the thermistor and estimates the patient's temperature based on the successive samples. If a predetermined number of successive temperature estimates lie within a predetermined error range, the sampling is terminated and the most recent estimate is displayed as the patient's temperature.