Triglycerides, cholesterol and phospholipids in serum and high density lipoproteins (HDL) were assessed in 11 women with previous gestational diabetes before and repeatedly during 6 months of low dose progestogen (lynoestrenol = LYN) contraceptive administration. Eight of these women also were followed in an identical manner during non-hormonal contraception (IUD) and 6 of them during combined oral contraceptive administration (EE + LYN). During the use of IUD or LYN administration neither serum nor HDL lipids changed. The combined OC, EE + LYN, increased serum triglycerides progressively: 73% (P less than 0.01) after 6 months concomitant with a 100%-increment of HDL triglycerides (P less than 0.01) HDL-cholesterol and -phospholipids were not consistently changed. The EE + LYN induced alterations differed from the effects of LYN alone (P less than 0.01). During the use of IUD or LYN administration neither serum nor HDL lipids changed. The combined OC, EE + LYN, increased serum triglycerides progressively: 73% (P less than 0.01) after 6 months concomitant with a 100%-increment of HDL triglycerides (P less than 0.01). HDL-cholesterol and -phospholipids were not consistently changed. The EE + LYN induced alterations differed from the effects of LYN alone (P less than 0.01). These results suggest that low dose progestogens, such as LYN, could be considered as contraceptive alternatives in women with gestational diabetes. However, combined OC should be avoided in these patients. The present findings differ from those obtained in insulin-dependent diabetics and suggest that a diabetic prediposition enhances the effects of synthetic oestrogens and/or diminishes some of the effects of progestogens on lipid metabolism.