Introduction: Acute ischemic stroke guidelines recommend endovascular therapy (EVT) for select patients with large vessel occlusion (LVO). A committee of stroke care providers from across MA pooled data to evaluate LVO related care and improve stroke systems of care. We sought to determine variation in care and factors associated with timeliness of Door To Start of Revascularization (first pass)(DTR). Methods: We analyzed 2018 patient-level Get with the Guidelines-Stroke data from 7 of 8 MA EVT-capable centers who provided consent for us to pool the data. Factors affecting DTR times were compared with univariate analysis (Kruskal-Wallis and t-tests as appropriate) and in linear regression models to identify those independently associated with DTR times, adjusted for patient characteristics and clustering by hospital. Variables included age, stroke severity, arrival on (M-F 7a-7p) vs. off hours, mode of arrival (EMS from scene vs interhospital transfer), and hospital EVT volume. Results: Median DTR for 317 patients from 7 centers was 89 (IQR 59-128) min. Site-specific median DTR times varied from 58 (IQR 30-93) to 137.5 (IQR 80.5-171.5) min. In univariate comparisons, median DTR times were shorter after interhospital transfer than EMS from scene (74 (IQR 45-108) vs. 114 (IQR 89-151) min, p<0.001). After controlling for other characteristics, stroke severity, mode of arrival, and off-hours arrival were significantly associated with DTR times, but hospital EVT volume was not (Table). Conclusion: Analysis of GWTG-Stroke data for MA demonstrates variability in hospital-level DTR times, with LVO patients presenting during off hours/holidays experiencing delays in DTR. Reassuringly, patients with more severe strokes were more likely to have shorter DTR times. While hospital EVT volume was not significant, this may be due to small sample size. This variability in performance suggests opportunities for improvement in the MA stroke systems of care.