Introduction: The left atrial appendage (LAA) morphology is classified into 4 categories: chicken wing (CW), windsock, cactus, and cauliflower (cLAA-CS) (Figure) without established inter and intra-rater agreements. We aim to determine intra-rater and inter-rater agreements and relationship with embolic stroke subtypes using a new classification system vs. cLAA-CS. Methods: Consecutive patients with ischemic stroke from a prospective stroke registry who previously underwent a clinically-indicated chest CT were included. Stroke subtype was determined and LAA morphology were classified using the cLAA-CS (CW=low risk) and the new LAA-H/L system [Low risk morphology (LAA-L) defined an acute angle bend or fold from the proximal/middle portion of the LAA and LAA-H defined as all others]. We determined intra and inter-rater agreements for the two classification systems and the association between non-CW and LAA-H morphologies with embolic subtypes in our cohort and stroke in previous studies. Results: We identified 329 patients with a qualifying chest CT performed (126 cardioembolic subtype, 116 ESUS, and 87 non-cardioembolic subtypes). Intra and inter-rater agreements improved using the LAA-H/L (0.95 and 0.85) vs. cLAA-CS (0.4 and 0.5). Using the LAA-H/L led to classifying 50 LAA morphologies that met criteria for CW as LAA-H (Figure). In fully adjusted models, LAA-H was associated with cardioembolic stroke (OR 5.4, 95%CI 2.1-13.7) and ESUS (OR 2.8 95% CI 1.2-6.4). Non-CW morphology was also associated with embolic stroke subtypes, but the effect size was much less pronounced. Studies using the cLAA-CS yielded mixed results for inter and intrarater agreements but most showed an association between a non-CW morphology and stroke with no difference among the three non-CW subtypes (Table). Conclusion: The LAA-H/L classification system is simple, has excellent intra and inter-rater agreements, and may help risk stratify patients at risk for cardioembolic stroke.