During the placebo lead-in phase (duration 3 to 4 weeks), patients will discontinue concomitant treatment with any antihypertensive or vasodilating agents and will receive single-blind placebo until randomization. Patients who meet the inclusion and exclusion criteria will be randomized to receive once-daily oral doses of either 2.5, 10, 35 or 50 mg AVE7688, or 100 mg losartan-potassium.