The presence of a macromolecule which binds androgen with a high affinity and a low capacity was demonstrated in the cytosol of the lacrimal glands of male and female rats. Evidence was found that this macromolecule was a protein by treatment with protease, trypsin or heat. A specific 8-8.5 S peak was obtained in both sexes by glycerol gradient centrifugation in low salt condition, whereas a specific 5.2 S peak was found in high salt condition. This protein could bind to DNA-cellulose after treatment of androgen-cytosol complexes by warming (25 degrees C 15 min) or exposure under high salt (0.4 M KCl). These results suggested that this protein was an androgen receptor.