The antihypertensive effect of the following therapeutic regimens: diuretic alone (DA), diuretic plus sympathetic inhibitor (DSI), diuretic plus betablocker (DB) and diuretic plus, betablocker plus vasodilator (DBV) was studied for 34.1 +/- 5.4 months in 28 patients with resistant essential hypertension (REH). Depending of treatment tolerability and the optimal antihypertensive action of drugs 21, 24, 26 and 10 cases were treated continuously or alternately with DA (9.9), DSI (15.0), DB (4.8), and DBV (14.6), respectively (in paragraph average duration of treatment in months). On admission the 89.3% and 42.8% of population had electrocardiographic signs of left ventricular hypertrophy or past-history of cardio-vascular complications, respectively. Arithmethic average and standard deviation of individual changes of systolic and diastolic blood pressure obtained during DA, DSI, DB and DBV treatment were -32.4 +/- 31.8, -19.3 +/- 27.2, -18.9 +/- 15.9 and -18.2 +/- 21.3 for systolic and -35.8 +/- 20.2, -12.3 +/- 17.2, -15.1 +/- 16.9 and -15 +/- 13.1 (mm. de Hg.) for diastolic blood pressure respectively. Average blood pressure before treatment was 222.4 +/- 30.3/128.0 +/- 20.8 (mm of Hg) and under the most effective treatment was 175.5 +/- 21.8/106.5 +/- 12.1 with a p less than or equal to 0.001 for either sistolic and diastolic pressure. There were not significant regressive electrocardiographic changes during the therapeutic period, neither significant changes in urea and creatinine blood values. 46.4% and 25% of cases exhibited collateral drug symptoms and cardio-vascular no fatal complications, respectively. Three of the last group patients died outside of the Hospital (2 sudden deaths and 1 renal insufficiency death). RH still constitutes a challenge to medical therapy. Nevertheless individualized therapy may modify the natural history of this hypertensive variety.