The nature of changes in the parameters of acoustic emission (AE) was examined for a variety of structural materials under fatigue test. The analysis of the behavior of AE suggests it is reflecting the main regularities of the failure process. In particular, depending on changes in the parameters of AE, was made the suggestion allocate the destruction conditions as follows: “fragile”, “plastic” and “fragile-ductile”. An analysis for possibilities of the predestruction criteria for different types of fatigue failures was made.