Transferrin and its receptor are involved in the delivery of iron to most cells. Previous studies have demonstrated that transferrin is associated with oligodendrocytes, the myelin-producing cells in the central nervous system. In the peripheral nervous system, the Schwann cell produces myelin. This study used immunohistochemistry and immunoblot analysis to determine whether expression of transferrin is unique to myelinated peripheral nerves. Immunohistochemical examination demonstrated cytoplasmic accumulation of transferrin in Schwann cells of the myelinated sciatic nerve, but not in the unmyelinated cervical sympathetic trunk. Immunoblot analysis revealed there is 10 X the amount of transferrin in the sciatic nerve compared to the cervical sympathetic trunk. These results are consistent with the hypothesis that transferrin may play a role in myelination.