Thrombotic thrombocytopenic purpura is a rare complication of ticlopidine treatment. This syndrome has been reported to occur typically within the first few weeks after the initiation of therapy. The authors describe a case of a 72-year-old woman in whom thrombotic thrombocytopenic purpura developed just 2 days after starting ticlopidine therapy for a new-onset ischemic stroke. The patient responded successfully to plasmapheresis. The authors are reporting this case to emphasize the unpredictable nature of the association between the drug and the disease, which necessitates careful hematologic monitoring.