The majority of patients with essential hypertension of moderate severity (WHO grade 2) require combination therapy. We aimed to investigate whether the single-pill combination of aliskiren 300 mg and hydrochlorothiazide (HCT) 25 mg (ALIS 300/HCT 25) improves the BP reduction in hypertensive patients not adequately controlled by the free combination of candesartan 32 mg and HCT 25 mg (CAN 32 + HCT 25).