Introduction. It has been demonstrated that kidney length is associated with office blood pressure (BP) measurements. Several studies support that ambulatory BP measurements in comparison to conventional BP better correlate with hypertensive target organ damage, and that the lack of nocturnal dip in BP (nondipping) is related to an increase in the incidence of cardiovascular event in essential hypertensive patients. This study evaluated the specific relationship between kidney length, renal cortical thickness (RCT), and circadian BP in hypertensive patients.