The evaluation of fatigue limit-σ−1 for AlSi7Mg, AlCu6Mn aluminum alloys is frequently encounter in material testing. In this method there is necessity of manufacture of test-tube from tested material or detail and made tension test.. There is destructive method. For many details there is not acceptable. Calculated in the usual ways fatigue limit appear only their statistical averaging between a number of structural factors indicating the influence. In material testing there is interest to non-destructive evaluation of fatigue limit σ−1 for the specimens and details. In this paper is lock at possibility for non-destructive evaluation of fatigue limit σ−1 by means measure velocities of propagation of longitudinal and transversal ultrasonic waves – VL and VT in tested materials and details.