To characterize the haemodynamic effects of diuretics, betablockers and the association of both, 24 hypertensive patients, stages I-II WHO criteria, were studied. Two haemodynamic studies were performed, before under placebo and after two month of active drug therapy. Seven patients received propranolol (PPL) (160-240 mg/day); 7 patients, hydrochlorothiazide (HCT) (150-100 mg/day), and 10 a combined fixed dose of pindolol (PDL) and clopamide (CLP): PDL 10 mg, CLP 5 mg per tablet, each patient receiving one to three tablets according blood pressure response. The haemodynamic study was performed with percutaneous intravenous flow-directed. Swan-Ganz catheter, associated with direct puncture of femoral artery and measuring cardiac output by thermodilution. Arterial pressure was significantly reduced on PPL (p less than 0.05) and PDL-CLP (p less than 0.01) groups, but not in the HCT group. The cardiac index was reduced by PPL (p less than 0.05) but not by HCT and PDL-CLP. The systemic vascular resistance was only reduced in the PDL-CLP group (p less than 0.05). The use of a betablocker with intrinsic sympathetic activity (ISA) (pindolol) in association with a thiazide diuretic (clopamide) seems to induce a favourable change in systemic resistance without a deleterious change in cardiac output as occurred with propranolol.