Abstract: A fat depth measuring apparatus and method for use in measuring in an animal the depth of a fat layer between hide and muscle. An ultrasonic generator generates ultrasonic pulses and an ultrasonic echo detector generates echo signals indicative of ultrasonic pulses received by the detector after reflection from boundaries or discontinuities within the tissues of the animal. Variable gain amplifier amplifies the echo signals and produces detector signals. Gain control means varies the gain of the amplifier to increase the probability of having exactly two detector signals identifiable as arising from echoes from a hide/fat boundary and a fat/muscle boundary. A fat depth determining means receives the detector signals and if they exceed primary threshold levels identifies the two required detector signals so as to thereby enable determination of the depth of the fat layer. If more than three detector signals have levels exceeding 60% of the threshold level, the depth determination is considered invalid.