A nondestructive method, capable of detecting localized surface damage, such as small spalls, nicks, dents and scratches, on the balls (rollers) and races of assembled rolling-element bearings, is discussed. The method utilizes the “almost periodical” character of vibration peaks produced by rotating a damaged bearing at constant speed. These “almost periodical” peaks are compared to the random vibration peaks, generated by the undamaged portions of the rolling surfaces of the bearing. Instrumentation to accomplish this comparison is described. It includes a vibration test spindle with pickup and amplifier, electronic gating circuitry serving as frequency and phase discriminator, and electronic counters to count “almost periodic” and random vibration peaks. Different methods of interpreting the counts and evaluating the degree of bearing damage are discussed.