A new revolutionary attitude toward investigation of fatigue damage in cyclically loaded steel samples is reported. The measurement is based on the method of magnetic adaptive testing, which-–in contrast to traditional magnetic hysteresis investigations-–picks up the relevant information from systematic measurement and evaluation of whole minor magnetic hysteresis loops and their derivatives. Satisfactory correlations between nondestructively measured magnetic descriptors and actual lifetime of the fatigued material were found. The presented method is able to serve as a powerful tool for indication of changes, which occur in the structure of the inspected objects during their industrial service lifetime, as long as they are manufactured from ferromagnetic materials.