A method and an apparatus for the post-process check of the workpieces machined by a double-plate lapping machine, in which the upper plate (1) is associated to means (5) controlling the lowering and the pressure applied on the workpieces, and the lower plate (16) is provided with a probe (15) able to detect the spacing from the upper plate and to feed a signal representing said spacing to an electronic meter (11), in which the corrected value F(K) obtained from the difference between the heights of the workpieces at the end of the first two machining cycle is set, said value being compared with the average of the values provided by a feeler pin (14) detecting the thickness of four lapped workpieces located at diametrally opposed positions at the end of each machining cycle so as to provide a further correction signal considering the variable parameters from cycle to cycle, said correction signal being fed to the central data processing unit (10) for the resetting thereof.