Clopidogrel is used as a frontline antiplatelet drug in patients with coronary artery disease, peripheral vascular disease and cerebrovascular disease. Though it is frequently reported that clopidogrel is associated with thrombotic thrombocytopenic purpura (TTP), severe isolated thrombocytopenia induced by this drug is rare. Here we report a case with isolated thrombocytopenia due to clopidogrel therapy. As this agent is widely used in clinical practice, the occurrence of this rare but dangerous adverse effect should be considered.