An electronic thermometer providing an improved means for controlling temperature readout. The thermometer incorporates analog-to-digital conversion utilizing a pulse width modulation technique. The temperature of a patient is taken for a given time interval and the last reading thereof is held for another given time interval. An adjustable oscillator provides clock pulses to a frequency divider one output of which triggers a saw tooth generator and other outputs of which are coupled to a decoder driving the display. The saw tooth generator provides an input to a reference comparator and a temperature measurement comparator the former of which receives a reference voltage and the latter of which receives a temperature sensitive voltage derived from circuitry which includes a thermistor. The outputs from the comparators are coupled through a hold-release circuit utilized to prevent erroneous readings due to premature release of an off-on switch, with the output from the hold-release circuit being coupled to the counter-display decoder to control the number of pulses therefrom fed through drivers to the digital readout display. The patient's temperature is continually displayed for a given time interval.