Analogues of the alpha, beta and gamma subunits of human spectrin and erythroid protein 4.1 have been detected in rat Sertoli cell primary cultures. Immunofluorescence of permeabilized cells showed that erythroid type spectrin, protein 4.1 and actin co-distribute within the cells as filamentous structures. Fodrin-like molecules were distributed in a diffuse manner, mostly associated with the plasma membrane. Immunoprecipitation and immunoblotting experiments indicated that the polypeptides present in rat Sertoli cells are immunologically related and display molecular weights similar to their analogues in the human erythroid and non-erythroid membrane skeleton.