Abstract
A 43-yr.-old man with Cushing''s syndrome who responded normally to corticotropin-zinc hydroxide and subnormally to metyrapone, did not suppress his cortisol production with the usual doses of dexamethasone. He was found to have bilateral adrenal hyperplasia with a well-encapsulated cortical nodule. It is proposed that these findings may represent a transition from hyperplasia to neoplasia.