Three oral contraceptive preparations were studied in 60 healthy women. This randomized, comparative, baseline controlled study was designed to investigate the effects of the preparations on plasma lipids and lipoproteins. The following formulations were studied: a monophasic preparation containing ethinylestradiol and desogestrel (M-DSG) and two triphasic formulations containing ethinylestradiol and gestodene or levonorgestrel respectively (T-GSD and T-LNG). These preparations were studied for six treatment cycles. Total cholesterol and apoprotein B did not change in any group. Low density lipoprotein (LDL) cholesterol was significantly decreased in the groups of women treated with M-DSG and T-GSD respectively. No changes were observed in the T-LNG group. With M-DSG, significant increases were observed in high-density lipoprotein (HDL) cholesterol and HDL3 cholesterol, whilst HDL2 cholesterol did not change. With both T-GSD and T-LNG, no changes were observed in HDL cholesterol, whilst a significant increase in HDL3 cholesterol together with a trend to decrease in HDL2 cholesterol were observed. Apolipoprotein AI increased with the following ranking M-DSG greater than T-GSD greater than T-LNG. The LDL/HDL cholesterol ratio significantly decreased with both M-DSG and T-GSD. In the T-LNG group there was no change in this ratio. Triglycerides increased to the same extent in all treatment groups. As far as concerns the risk of arterial diseases, these three oral contraceptive formulations mostly induced negligible and/or partly favorable changes in plasma lipids and lipoproteins; however, the lipoprotein pattern during M-DSG treatment resulted better than during T-GSD, and the latter turned out to be better than during T-LNG.