Neurofascin, one of the members of L1CAM, has been known to have some important roles during the development of nerve fibers. In order to investigate the role of neurofascin associated with the development of nerve fibers in the rat sciatic nerve, the initial development of NF155 in the paranode was studied with immuno-fluorescence and immuno-electron microscopy. The result of the present study showed NF155 was not detected in the fetal sciatic nerve and began to reveal at the postnatal day 0 (P0) and dramatically increased by time lapse until postnatal day 7 (P7). NF155 was prominently localized in the axolemma of paranode and not detected in the central region of node of Ranvier. According to the present study, NF155 is likely to have some relationships with the formation of paranode and myelin sheath.