Protein C and protein S deficiencies may uncommonly be responsible for coronary arterial thrombosis. We report a young woman with recurrent acute stent thrombosis due to the deficiency of protein C and S. After coronary stenting, stent thrombosis occurred two times despite aggressive antiplatelet therapy, including aspirin, clopidogrel and glycoprotein IIb/IIIa inhibitor. This report suggests that the deficiency of protein C and S should be born in mind in a young patient with recurrent thrombotic events, and that anticoagulants in addition to antiplatelet agents considered in the presence of their deficiency.