Until recently, adrenal masses came to clinical attention either from local symptoms due to massive enlargement or from manifestations of excess hormone production. During the last year, an adrenal mass was identified as an incidental finding in 9 patients undergoing abdominal computed tomographic (CT) scanning for unrelated problems. These 5 men and 4 women ranged in age from 41-73 yr. Eight were hypertensive. After the CT scan, each was evaluated for catecholamine or steroid hypersecretion. Only one had clearly elevated urinary vanillylmandelic acid, metanephrine and catecholamine levels. Equivocal evidence of catecholamine excess was seen in 5 patients who had slight elevation of 1 urinary metabolite or of plasma epinephrine or norepinephrine levels. Three patients had no evidence of medullary or cortical hyperfunction on repeated testing. Eight patients were good operative risks and underwent unilateral adrenalectomy without complication. Masses ranging in size from 1-4 cm were found in each. These included 4 cortical adenomas, 2 adrenal cysts, 1 adrenal lipoma and 1 pheochromocytoma. The pheochromocytoma occurred in the patient with strong biochemical evidence of disease. With wider application of Ct imaging, increasing numbers of asymtpomatic adrneal masses will be detected. Care in interpreting the clinical significance of these masses and caution in recommending treatment are required.