In the present work, Distaloy AE powder metallurgy (PM) steel, in as-sintered state are experienced under uniaxial fatigue tests in a range of tensile mean stresses. Microstructural investigations reveal that for tensile mean stress, pores are widened and easily linked up by cracks. Moreover, with obtained fatigue results, well-known fatigue failure criteria, such as Goodman, Gerber and Morrow, are employed to the experimental data. The result shows that the experimental data for Distaloy AE porous sintered steel are well suited to these criteria especially in the case of Morrow and Gerber failure criteria. Furthermore, the alteration of samples length versus cycles shows the cyclic hardening behaviour for this diffusion-bonded PM steel. It seems that this concept is a reason for increasing the fatigue property of diffusion-bonded steels in comparison with other PM Steels.