Abstract: A thermometer for temperature measurement of a body is provided wherein a temperature probe electrically connects to a temperature read-out means and a probe cover or sheath fits over such probe. The sheath has a temperature sensor e.g. a thermistor mounted thereon, which sensor is electrically connected to the probe when such probe is inserted into such sheath to provide a rapid measurement and read-out of the temperature of a body. The sheath with temperature sensor is disposable and readily replaced for the next use of the electric thermometer of the invention. Alternatively, the sheath can be sterilized for reuse.