The aim of this study was to compare the effects of a beta-blocker (mepindolol) with intrinsic sympathomimetic activity (ISA) to a beta-blocker (metoprolol duriles) without ISA. Hypertensive patients with more than 50 years of age were selected and randomly allocated to receive either 5 mg/day mepindolol (Group A, 10 patients), or 200 mg/day metoprolol duriles (Group B, 9 patients), or placebo (Group C, 10 patients). They were submitted to clinical exam, stress testing and plasma lipids dosage before and after four weeks of treatment. At rest, there were a significant reduction of systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) in all groups. The mean values for SBP, DBP and HR at rest after treatment were respectively: 154.0, 95.5, 73.7 (Group A); 148.8, 94.4, 70.1 (Group B); 153.0, 96.0, 77.8; (Group C). During stress testing, there were a significant reduction of SBP, HR and double product (DP). The DBP remained unchanged. The mean values for SBP, DBP, HR and DP during stress testing after treatment were respectively; 198.0, 115.5, 124.3, 246.9 (Group A); 198.8, 114.4, 144.6, 283.2 (Group B); 202.2, 119.0, 143.5, 283.4 (Group C). Total cholesterol, HDL-cholesterol, and LDL-cholesterol, have not changed with both beta-blockers. There were a significant increase in plasma triglycerides and VLDL-cholesterol levels after treatment with beta-blockers. In conclusion, both mepindolol and metoprolol were similarly effective in reducing arterial blood pressure of hypertensive patients. There were not significant differences between the beta-blocker with or without ISA in regard to their effects on plasma lipids.