Abstract: Method for determining the position and depth of unevenness in an inner surface of a pipe with the aid of a scanning head which is adapted to travel through the pipe and which is rotatable about the pipe axis. The invention provides an inductive, or capacitive, depth scanning process, which operates in a contact-free manner with respect to the inner pipe surface. This is attained by means of an inductive method in that, as is illustrated in the drawing, there is arranged at a distance from the pipe inner surface the scanning head which is guided and in which a coil (2) of a measuring, resonant circuit is mounted and, above the inner periphery of the pipe, a coil 1 of a reference, resonant circuit is arranged, and then, after the frequencies of both resonant circuits have been brought, prior to measuring, to an identical value in each of a multiplying circuit (10, 7, 13 respectively 11, 8, 14), they are measured and converted into an adjustable difference of the multiplied frequencies (f.sub.1, f.sub.