Study population: 212 hypertensives recruited from primary care assistance (time since first diagnosis of hypertension: 16.5±8.1 years) and without appropriate pressure control, between 2001 and 2006, corresponding to 0.48% of all hypertensives under care (18 new cases/year), 57±10 years old, 66% females. Under drug treatment schedule: three or more drugs including a diuretic. Ninety two randomly selected hypertensives basis had renin-angiotensin-aldosterone system genetic profile determined. Genetic assessment was carried out using a polymerase chain reaction assay amplification technique. The following single nucleotide polymorphisms were analyzed: renin (G1051A), angiotensinogen (M235T), angiotensin converting enzyme-ACE (I/D), angiotensin II type 1 receptor (A1166C), aldosterone synthase (C344T) and mineralocorticoid receptor (G3514C).