Despite best practice replacement therapy with corticosteroids, patients with adrenal insufficiency report diminished quality of life and face increased mortality and morbidity. Conventional formulations of hydrocortisone have short half-lives (about 90 minutes) requiring multiple dosing during the day. Since 2011, extended-release hydrocortisone (ER-HC) formulations have been available enabling once-, sometimes twice-daily dosing. Most studies comparing ER-HC formulations with conventional hydrocortisone therapy report reduction in body weight, blood pressure and glucose levels, and improved quality of life. However, it is still unclear if the reported beneficiary effects are due to differences in cortisol exposure or alterations in pharmacokinetics. Here, we review studies comparing conventional and ER-HC treatment in adrenal insufficiency and discuss whether these novel formulations are safe and offer clinically significant benefits.