A case is reported of epidermoid carcinoma of the lung of a 64-year-old white male which was associated with extreme bilateral adrenocortical hyperplasia, the adrenals weighing 54 gm. Although this patient exhibited a markedly exaggerated free and conjugated plasma 17-hydroxycorticosteroid response to conventional ACTH, no objective evidence of either hyper- or hypoadrenocorticism was present during his entire clinical course. It is postulated that the adrenal hyperplasia is due to the action of an unidentified adrenal growth factor, which did not affect adrenocortical secretion.