Three groups of hyperlipoproteinemia patients have been submitted to long term treatment (18 months) with bezafibrate, gemfibrate and fenofibrate evaluating efficacy and tolerability of the three drugs. A global improvement of lipemic profile with an increase in protective (HDL, APO-A1) and a reduction in atherogenic factors (TC, LDL, APO-B, TG) has been shown, particularly at the end of the 18 months of therapy. No pathological changes have been observed in SGOT, SGPT, GGT values. Echotomography of biliary tract excluded the development of gallstones during treatment. The Authors can conclude with a positive judgement about use of these drugs in long term treatment of primary hyperlipoproteinemias, resistant to diet alone.