Abstract: Apparatus (2) for measuring the quality of spot welds, comprising a housing (4); a fluid medium (6) in the housing (4); transmitter means (8) for transmitting at least one ultrasonic pulse through the fluid medium (6) to a spot weld (10), the ultrasonic pulse then reverberating in the spot weld (10); and receiver means (16) through which the ultrasonic pulse passes on its way to the spot weld (10), the receiver means (16) being ultrasonically sensitive so that it is able to receive echoes from the spot weld (10) by the reverberation of the ultrasonic pulse in the spot weld (10), the receiver means (16) comprising a plurality of ultrasonically sensitive elements (18), and the receiver means (16) being such that during use of the apparatus (2) the receiver means (16) is located adjacent the spot weld (10).