We have studied the production and release of inhibin-like immunoreactivity in the human adrenal gland. Extract of human adrenal glands showed a displacement curve paralled with the inhibin standard. Inhibin-like immunoreactivity contents in the adrenal gland was 1893±474 (mean±S.D.) IU/g wet weight tissue. ACTH stimulated the secretion of inhibin-like immunoreactivity as well as cortisol and aldosterone in a dose-dependent manner in the cultured adrenal cells. These results indicate that the human adrenal gland produces and secretes inhibin-like peptide in response to ACTH.