The antiplatelet drug clopidogrel has largely replaced ticlopidine, due to an association between ticlopidine and thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS). Clopidogrel at first was thought to be void of this potentially fatal adverse effect, but recent case reports have called that assumption into question. Even with proper treatment (plasma exchange), TTP-HUS can persist for weeks. Clinicians should be aware of this possible adverse effect because prompt therapy is imperative for patients' survival. Earlier reports of clopidogrel-related TTP-HUS have involved patients who had received at least 72 hours of therapy. We describe a case of TTP-HUS in a patient who had received only a 300-mg loading dose of clopidogrel.