To analyze the control degree and characteristics of arterial pressure (AP) obtained with monotherapy.A sample was obtained of 277 hypertensive patients (83 men and 194 women) on monotherapy from cluster sampling. All included patients were older than 18 years and had essential hypertension (HBP). Both systolic and diastolic pressure values (mean of two measurements), prescribed drug, age and sex were recorded.Less than 30% of subjects had adequate control (< 140/90), mainly because of poor control of systolic BP. The drug group most commonly was ACEI, followed by calcium blockers (CAB); enalapril and chlortalidone were the most commonly prescribed drugs. Diuretics were used most frequently by women (OR 4.2). The use of diuretics, calcium channel antagonists and alphaadrenergic blockers increased with age. The opposite was true for ACEI and beta blockers.A poor control of HBP in patients on monotherapy was observed, particularly for the systolic component. There is a higher use of ACEI and HBP. There is a highly significant difference regarding the use of diuretics between men and women which has no theoretical basis.