The existence of a functional link between the nervous and immune systems has been well established. The present study was to characterize the expression of p75^NTR^ during thymus regeneration from acute involution induced by cyclophosphamide in the rat. Immunohistochemical and double immunofluorescence analyses demonstrated that expression of the p75^NTR^ was decreased in the thymic medullary epithelial cells and interdigitating dendritic cells during thymus regeneration. The presence of p75^NTR^ protein in extracts from the control and regenerating rat thymus was confirmed by western blot. Furthermore. RT-PCR analysis supported these results by demonstrating that thymic extracts contain p75^NTR^ mRNA at lower levels during thymus regeneration. Thus, our results suggest that the p75^NTR^ located on the thymic medullary epithelial cells and interdigitating dendritic cells could play a role in the development of new T cells to replace the thymocytes damaged during thymus regeneration.