A case of Sertoli-cell carcinoma of the ovary associated with Cushing's syndrome was studied. The patient failed to respond to dexamethasone suppression and gave an exaggerated response to a corticotropin drip. The primary tumor removed at operation and the metastases found at autopsy contained a corticotropin-like material. Both adrenals at surgery were considered "normal" to palpation and 4 months later at autopsy were massively, bilaterally enlarged while the pituitary basophils showed Crooke-Russell hyalinization. After operation m,p'-DDD was administered with decreased plasma levels and urinary excretion of corticosteroids. The patient became refractory to a corticotropin drip and after withdrawals of the m,p'-DDD the corticosteroids increased. It appears that in this case the ovarian tumor was secreting a corticotropin-like material, the action of which was partially inhibited by m,p'-DDD.