Synthetic estrogens and progestins used in oral contraceptives (OCs) have inverse effects on lipoproteins: synthetic estrogens augment production of very low density lipoproteins (VLDL) and therefore of triglycerides, as well as of high density lipoproteins (HDL) and therefore of anti-atherogenic cholesterol which plays a clensing role in tissue cholesterol. Synthetic estrogens diminish production of low density lipoproteins (LDL), or atherogenic cholesterol. Norsteroid progestins have a strong anti-estrogenic action; they decrease cholesterolemia while lowering the rate of cholesterol tied to HDL. They also decrease the plasma level of VLDL. Derivatives of 17 OH progesterone do not seem to have these actions on lipoproteins. Things to do in treating OC users with abnormal lipid patterns include specifying the exact nature of the lipid abnormality by determining the plasma levels of triglycerides and total cholesterol and its fractions; comparing the lipid profile with the pattern before OC use so as to specify the type of anomalie; identifying family histories of diabetes, obesity, hyperlipidism, and cardiovascular pathology; inquiring about dietary habits, smoking, weight changes, and blood pressure; searching for the pathology responsable for lipid anomalies, which in the case of hypertriglyceridemia requires ruling out glycoregulation problems, diabetes, excessive alcohol consumption or use of diuretics, corticoids, or beta blockers and in the case of hypercholesterolemia involves hypothyroidism, cholestatic syndromes, nephropathies, or use of diuretics; and considering whether the progestin used in the OC is a potent anti-estrogenic capable of compensating for the hypertriglyceridemia provoked by the estrogen. In all cases of hyperlipidemia, regardless of the causes, pill use should be terminated and the patient should be followed up for 3 months to determine whether levels return to normal. The new contraceptive method may be nonhormonal or may be a minidosed progestin for obese, hypertensive, or diabetic women or normal dosed progestin for nondiabetic women with no risk factors and normal postprandial glucose levels. Things that should not be done in treating OC users with abnormal lipid patterns include neglecting to obtain baseline lipid and glucose profiles; failing to determine the lipid profiles and glucose tolerance after 6 months of pill use and at least once a year thereafter; prescribing the pill after age 40 or for women who are hyperlipidemic, diabetic, hypertensive, obese, smokers, or who have individual or family histories of vascular risk; or relying on a diet with reduced sugar and fats or a lower doses estrogen to resolve the problem.