 Patients with adrenal insufficiency are usually treated with conventional hydrocortisone replacement therapy which fails to mimic the circadian rhythm of cortisol secretion. Dual-release hydrocortisone (DR-HC) resembles the daily normal cortisol profile improving metabolic parameters and quality of life. However, currently little is known about its impact on cognitive function. Aim of this study was to evaluate cognitive function and well-being in DR-HC treated patients compared to healthy controls and conventional HC treatment.