A small scale yielding two-parameter modified boundary layer analysis is performed to study the occurrence of plasticity induced fatigue crack closure under constant amplitude plane strain conditions. A wide range of T-stress and K I levels are considered in the finite element analysis with the purpose of exploring the behavior of the crack opening stress. The influence of the T-stress on crack closure is shown. Crack closure was observed for some values of T-stress, while other values of T-stress resulted in an absence of closure under steady-state conditions.