Adrenal incidentalomas have become detected more often as the use of abdominal imaging has increased. Up to one-third of these may be secreting low levels of cortisol, known as mild hypercortisolism or subclinical Cushing syndrome. These low levels of cortisol have been found to be associated with an increased in the metabolic syndrome, osteoporosis, cardiovascular events, and mortality. This article discusses in detail the epidemiology, diagnosis, clinical associations, and treatment options of mild hypercortisolism.