Thirty subjects who satisfy the study criteria will be randomized to receive once daily therapy with either losartan 50 mg or hydrochlorothiazide 12.5 mg. Subjects will take study medication once daily between 06:30 and 11:00, and be followed up in morning clinic visits, scheduled between 06:30 and 11:00. Subjects will be instructed not to take their medication on the morning of clinic visits until after the clinic evaluations have been completed. During the 6 months of treatment, subjects will have their "trough" blood pressure, heart rate (HR) and body weight measured at every clinic visit. At visits where laboratory safety tests will be done, subjects will be asked to come fasting.