Cushing's syndrome is an uncommon disorder involving dysregulation of the hypothalamic-pituitary-adrenal axis resulting in endogenous hypercortisolemia. It has multiple causes, but most commonly is due to hypersecretion of corticotropin from the pituitary gland, called Cushing's disease. The diagnosis of Cushing's syndrome remains a challenge to clinicians because routine hormonal assays can have significant overlap in pathological and normal states. We will review an approach to evaluating patients with suspected cortisol excess. We will also discuss treatment options and post-surgical assessment for those diagnosed with Cushing's disease.