Ischemic stroke, which often presents with non-specific symptoms and requires time-sensitive treatment, can be a source of diagnostic error and misdiagnosis. Using a large medical malpractice claims database, this study found that nearly half of all malpractice claims involving ischemic stroke included diagnostic errors, primarily originating in the ED. The analysis found that breakdowns in the initial patient-provider encounter (e.g., history and physical examination, symptom assessment, and ordering of diagnostic tests) contributed to most malpractice claims.