The purpose of this study is to evaluate the antihypertensive response of treatment with losartan with reference to genetic polymorphisms.

Inclusion Criteria:

• Both gender less than 60 years old, with mild-moderate hypertension (SBP greater than and DBP equal or greater than 90 mmhg, BP < 180/110)
• Never treated for hypertension or who have taken antihypertensive agents sporadically (not more than 15 days total therapy) but not in the 30 days prior to the first visit
• Patient in therapeutic wash out for 6 months
• Patient is asymptomatic, absence of significant concomitant diseases, except for non-familial hypercholesterolemia, absence of systemic diseases
• Women with menopause not treated with hormone replacement therapy or women of reproductive age who do not make use of estro-progestagen agents but who use another safe contraceptive method
• BMI < 30 for men and < 28 for women

Exclusion Criteria:

• Secondary or malignant hypertension, Na <130 mmol/l, K >5,5 mmol/l, or < 3,0 mmol/l
• Cardiac disease such as ischemic, HF, arrhythmia, cardiac surgery
• Pregnant, breast feeding
• History of nephropathy, metabolic disease, liver disease
• Alcohol or drug abuse
• History of angioedema
• Has a known hypersensibility to study drug(s)