Purpose of the Review: This article reviews the biochemical, structural, and imaging characteristics of intracranial thrombi in acute ischemic stroke; the relationship between thrombus composition and response to lytic and endovascular therapies; and current and future directions for improving outcomes in acute stroke patients based on thrombus characteristics.

Recent Findings: New imaging techniques have advanced our ability to capture thrombus characteristics and burden in real-time, An improved understanding of recanalization rates with thrombolysis and endovascular thrombectomy based on thrombi has spurred interest in new acute therapies for acute stroke.

Summary: Thrombus composition, size, location, and timing from stroke onset correlate with imaging findings in acute ischemic stroke and are associated with clinical outcome. Further research across multiple domains could assist in better applying our knowledge of thrombi to patient selection and individualization of acute therapies.