A measuring and evaluation method was developed to make a rapid and non-contacting gauging of the coat-thickness of covered wires. It is described with the aid of aluminium coated steel wires. In preliminary tests lite β-backscattering principle was found as the best measuring method. With a gauging head developed for this prupose 20 probes were measured on 4 positions each staggered at 90° and the coat-thickness as well as the maxima and minima were calculated. A comparison with those values measured on conventional mode with a microscope showed a perfect consistency. The accuracy is better than ±0·01 mm. The time of investigation can be less than 1 minute and the apparatus can also be used for on-line gauging direct on drawing or coating plants. A proposal for a non-contacting measuring of the total diameter of the wires is made.