: The authors describe a 15-year-old girl presenting with a cerebral ischemic stroke as the first manifestation of catastrophic antiphospholipid antibody syndrome secondary to acute myeloid leukemia (AML). Despite treatment with anticoagulants, therapeutic plasma exchange, and chemotherapy, the patient developed multiorgan thromboses and failure, eventually culminating in death. This unusual presentation of AML has not been previously described in children. Clinical features of antiphospholipid antibody syndrome and current knowledge regarding its association with malignancies are reviewed.