This review summarizes recent data on the effects of endogenous and exogenous androgens, estrogens and progesterone on serum lipoproteins levels and composition in humans. Sex steroid hormones modulate serum lipoprotein metabolic mechanisms and influence atherosclerosis and coronary heart disease. In general, androgens lower HDL and raise LDL levels and Lp(a) thus promoting the atherogenic process. As it is true with estrogens, the lipoprotein effects of androgens are more pronounced with oral than with parenteral administration. Millions of women use oral contraception and postmenopausal women use more and more some form of hormone replacement therapy. The HDL-raising effect of estrogen replacement seems to be mediated by an increase in apoprotein AI production and not by a decrease in the clearance rate. Estrogens lower LDL levels by accelerating the rate of LDL catabolism which is due to an increase in the number of hepatic LDL receptors. They also improve endothelium-dependent vasodilatation which might be mediated by an antioxidant action of estrogens. These facts could explain well known cardioprotective effects of estrogens. Androgen progestins, especially older such as norgestrel, lower HDL and raise LDL thus diminishing or eliminating the benefits of estrogens on cardiovascular system while newer progestins have a lesser effect on circulating lipoproteins.