An increasing attention has been devoted in the last two decades to masked hypertension (MH), a condition characterized by the fact that classification of a normal blood pressure (BP) status by office measurements is not confirmed by home and/or ambulatory BP monitoring (ABPM). MH definition (i.e., normal office BP, but high out-of-office BP) should be restricted to untreated subjects (true MH) whereas masked uncontrolled hypertension (MUCH) reserved to treated patients previously classified as hypertensives, presenting normal office BP and high ABPM or home values. Both MH and MUCH are associated with metabolic alterations, comorbidities, and hypertension-mediated organ damage (HMOD). Furthermore, the risk of cardiovascular events related to these conditions has been shown to be close or greater than that of sustained hypertension. This review discusses available evidence about MH and MUCH by focusing on its prevalence, clinical correlates, association with HMOD, prognostic significance, and their therapeutic implications.