In this study, hypoeutectoid Fe-N binary specimens have been prepared by gas nitriding pure iron in austenite domain at 840 A degrees C. The slow cooling of these specimens led to the alpha-ferrite + gamma'-Fe4N pearlitic microstructure which is similar to the pearlite in Fe-C binary system. This pearlitic microstructure has been characterized by electron microscopy. The crystal structure of the gamma'-Fe4N nitride has been identified by electron microdiffraction and the Nishiyama-Wassermann (N-W) and near Kurdjumov-Sachs (K-S) orientation relationships have been found between the alpha-ferrite and the gamma'-Fe4N.