A 50-year-old Caucasian woman who took gestodene 75 μg/ethinylestradiol 20 μg as oral contraceptive, was sent to our thrombophilia clinic because, on thrombophilia testing, a reduction of SERPINC1 (74%) and a slight increase in circulating D-dimer and homocysteine were found. The gene discussed is SERPINC1; the disease is Rare hereditary thrombophilia.