Background: Patients with renovascular hypertension (RVH) have a higher degree of cardiovascular end-organ damage compared to patients with essential hypertension (EH). The precise mechanisms underlying this phenomenon, however, have not been fully elucidated. This study investigated the relationship between circadian blood pressure (BP) profile and cardiac involvement in patients with RVH and EH. Methods: Twenty patients with RVH and 20 with EH, matched for demographic characteristics, underwent simultaneous 24-hour ambulatory BP recording and Holter ECG monitoring. Also, each participant underwent echocardiographic assessment of left ventricular mass. Cardiac damage was defined as the presence of left ventricular hypertrophy, myocardial ischemia or arrhythmias. Results: Casual BP was similar in both groups, whereas 24-hour ambulatory BP values were higher in RVH than in EH patients; moreover, RVH patients had higher blood pressure variability and blunted nocturnal BP fall compared to those with EH. Left ventricular mass, as well as the prevalence of myocardial ischemia and the presence and severity of cardiac arrhythmias, were higher in RVH than in EH patients. Conclusions: Patients with RVH have altered circadian BP profile compared to those with EH. This abnormality might contribute to their increased prevalence of cardiac damage and might adversely affect the prognosis of these patients.