The expression of the neural cell adhesion molecule, N-CAM, was examined in the anterior lobe of rat hypophysis by immunocytochemistry at light and electron microscope levels. In addition, N-CAM antigenic determinants present in adrenal medulla, anterior hypophysis and PC12 cells were compared by immunoblotting with those found in cerebellum. All secretory cells in the anterior hypophysis were found to be N-CAM positive on their surfaces, but not all of the three polypeptide determinants typical of cerebellum were present in the endocrine tissues or cell line tested. In addition, a new N-CAM determinant of 49 kDa not present in cerebellum was found in adrenal medulla and hypophysis, although it was absent from PC12 cells. The possible implications of these data are discussed.