Subclinical Cushing's syndrome (CS) is attracting increasing interest since the serendipitous discovery of an adrenal mass has become a rather frequent event owing to the routine use of sophisticated radiologic techniques. Cortical adenoma is the most frequent type of adrenal incidentaloma accounting for approximately 50% of cases in surgical series and even greater shares in medical series. Incidentally discovered adrenal adenomas may secrete cortisol in an autonomous manner that is not fully restrained by pituitary feedback, in 5 to 20% of cases depending on study protocols and diagnostic criteria. The criteria for qualifying subclinical cortisol excess are controversial and presently there is no consensus on a gold standard for the diagnosis of this condition. An increased frequency of hypertension, central obesity, impaired glucose tolerance, diabetes and hyperlipemia has been described in patients with subclinical CS; however, there is still no clear demonstration of the long-term complications of this condition whose management remains largely empirical. Either adrenalectomy or careful observation associated with treatment of the metabolic syndrome have been suggested as treatment options.