Abstracf. The results of two randomized prospective studies on metabolic changes induced in groups of healthy Young women by commercial oral contraceptives (OC) are described. In the first study, four low-estrogen (30 pg or 35 pg ethinylestradiol) combined products were compared, while in the second, effects of four different formulations, each containing levonorgestrel plus ethinylestradiol, were determined. Results are presented for oral glucose tolerance and plasma insulin responses, serum total cholesterol, HDLcholesterol, triglycerides, coagulation factors I, VII, VIII, and x, plasminogen, anti-thrombin 111, and (for study no. two only) renin activity, substrate, and concentration. In