A case of hyponatremia, serum hypo-osmolality, urine hyperosmolality, with normal renal, hepatic, and cardiac function, and absence of adrenal insufficiency is reported in a patient with a documented metastatic carcinoma of the adrenal. Even though antidiuretic hormone was not assayed, all the criteria described in the syndrome of inappropriate secretion of antidiuretic hormone were met, representing the first so described association with a malignancy of the adrenal gland.