A case of severe hypercalcemia secondary to carcinoma of the lung is described in which hypokalemic alkalosis, renal failure and pancreatitis were also present. The relative importance of the few bone metastases found at autopsy is considered, and a probable endocrine-like effect of the tumour in the development of the hypercalcemia is postulated. Treatment of the hypercalcemia included administration of corticosteroids and disodium EDTA, peritoneal dialysis and subtotal parathyroidectomy; the most effective of these was peritoneal dialysis. Subtotal parathyroidectomy failed to produce a further decrease in serum calcium values. The occurrence of hypokalemic alkalosis in the presence of increased adrenocortical function and its relationship to the carcinoma of the lung are discussed. The possibility that this neoplasm produced two factors which caused systemic effects ordinarily associated with the function of endocrine glands must be considered.