A study of the coadministration of CellCept (1 g bid) and combined oral contraceptives containing ethinylestradiol (0.02 mg to 0.04 mg) and levonorgestrel (0.05 mg to 0.15 mg), desogestrel (0.15 mg) or gestodene (0.05 mg to 0.10 mg) conducted in 18 non-transplant women (not taking other immunosupressants) over 3 consecutive menstrual cycles showed no clinically relevant influence of CellCept on the ovulation suppressing action of the oral contraceptives.