Beta-blockers are frequently used in the treatment of hypertension. However their long term use has been associated with an increase of serum triglycerides and a decrease of HLD-cholesterol concentrations which could diminish the benefit drawn from their hypotensive effect. The effect on lipid metabolism is less unfavourable when beta-blockers exert an intrinsic sympathomimetic activity or are said to be cardioselective. Mechanisms involved are complex and poorly understood.