The investigation of fatigue behavior of auxetic porous structure made of Al-alloy 7075-T651 is presented in this study. The complete fatigue process of analyzed porous structure is divided into the crack initiation (Ni) and crack propagation (Np) period where the total fatigue life (Nt) is defined as: Nt = Ni + Np. The crack initiation period, Ni, is determined using strain life approach in the framework of FE-Safe computational code where elastic-plastic numerical analysis is performed to obtain the total strain amplitude in the critical cross section of the porous structure. The number of stress cycles, Np, required for the crack propagation from initial to the critical crack length is also numerically determined using finite element model in the framework of Abaqus computation FEM code. The Maximum Tensile Stress (MTS) criterion is considered when analyzing the crack path inside the porous structure.