Introduction: Subclinical Cushing's syndrome (SCS) is defined as biochemical overt cortisol excess in the absence of the classical signs and symptoms of Cushing's disease. The prevalence of SCS is reported as between approximately 5% and 24% in patients with adrenal incidentalomas (AI). SCS has increased cardiovascular and metabolic risk factors, and metabolic syndrome. Recently some studies demonstrated oxidative stress enhancement in Cushing's disease. Ischemia-modified albumin (IMA) is a marker of ischemia and oxidative stress and is increased in different clinical conditions such as cardiovascular diseases and metabolic syndrome. However, it has not been investigated in the patients with SCS. We aimed to evaluate serum IMA levels in the patients with SCS.