Effective and sustained control of blood pressure (BP) is crucial in preventing organ damage and cardiovascular (CV) complications from hypertension. However, only a minority of treated patients with hypertension achieve adequate BP control. This picture is complicated by the inherent limitations of traditional BP measurements in the physician’s office. BP consistently varies during the day because of several physical and psychological stressors, including the clinical visit. BP varies also from day to night, and 24-h ambulatory BP is strongly associated with the risk of subsequent CV disease. Therefore, BP monitoring should be performed for most patients with hypertension to assess the achievement of 24-h BP control. Among the available antihypertensive agents, olmesartan medoxomil has been shown to provide effective and sustained BP control over the entire-24-h period. The antihypertensive efficacy of olmesartan medoxomil has been investigated in patients with essential hypertension and diabetes, and even in children with hypertension. For patients who cannot be controlled by monotherapy, olmesartan is available in fixed combination with hydrochlorothiazide and amlodipine. A 3-drug fixed combination of olmesartan, hydrochlorothiazide, and amlodipine is available for patients who need 3 or more drugs to control BP. High-dose combinations have been associated with improvement of 24-h BP control.