The paper contains the results of fatigue tests of C45 steel and 2024 aluminum alloy under bending with the controlled amplitude of the moment and energy parameter. The circular smooth cross-section specimens were tested. All the fatigue tests were performed under a constant value of the nominal load ratio, R = - 1. The test frequency ranged from 11 to 15 Hz. During the tests, histories of stress, strains, energy parameters and hysteresis loops, (σ-ε), were measured and registered. Then, the fatigue test results obtained with the controlled energy parameter and bending moment were compared