Immunohistochemical localization of a neural cell adhesion molecule (NCAM) was examined in the subpial pontine migratory stream of the fetal rat with a monoclonal antibody specific for the rat NCAM, MAb-AF11. Although the pontine cell strand showed weaker expression of NCAM than the parenchymal areas of the brainstem, within the cell strand, NCAM-immunoreactivity was somewhat greater in the anterior part of the stream near the neurons' destination than the caudal part. The weak NCAM gradient in the pontine migratory stream may contribute to formation of the pontine cell strand and the basal pontine gray.