Forty-five hypertensive patients (I-II WHO), after two weeks wash out, were randomly allocated to receive 100 mg/day atenolol, 200 mg/day metoprolol and 10 mg/day mepindolol for three months, in order to evaluate their possible effect on lipid metabolism. Plasma triglyceride levels were increased by the three drug treatments; the increase was, however, greater after mepindolol. Total cholesterol was unchanged by atenolol, increased by metoprolol and decreased by mepindolol. HDL-cholesterol was unchanged by atenolol, decreased by metoprolol and increased by mepindolol, whereas LDL-cholesterol was increased by atenolol, unchanged by metoprolol and decreased by mepindolol. Therefore, the LDL/HDL ratio was decreased by mepindolol (from 3.15 +/- 1.71 to 2.92 +/- 1.17) and increased by atenolol and metoprolol. The results show that the treatment with atenolol, metoprolol and mepindolol does not significantly affect the lipid levels suggesting that cardioselective beta-blockers as well as those with ISA have no untoward effect on lipid metabolism.