We have used a polyclonal antibody to the biosynthetic adrenocortical enzyme, 3-beta-hydroxysteroid dehydrogenase, to demonstrate rat adrenal cortical tissue in situ, in vitro, and in intracerebral adrenal suspension grafts. This technique provides a means of identifying the degree to which adrenal medulla grafts are in practice contaminated by adrenal cortical cells and allows analysis of the extent to which the presence of cortical cells influences the viability, differentiation, and functional efficacy of intracerebral adrenal grafts.