Abstract only Background: Delays in endovascular therapy can lead to worse outcomes in stroke patients. Interfacility delays when transferring patients to thrombectomy-capable hospitals are common. We sought to identify causes of such delays and create a standardized transfer process to improve transfer times. Methods: A 15-hospital system formed a multidisciplinary team to assess the current state of DIDO processes from data on previous transfers, evaluate current transfer algorithms, and analyze baseline performance. Individual hospital transfer algorithms were compared. Results: Data was analyzed for 47 patients transferred from 12 facilities to thrombectomy-capable centers from June 2017 to July 2018 who received ischemic stroke treatment. 71% were from a metro area within 50 miles of a thrombectomy-capable hospital and 29% were from outside the metro area, up to 400 miles away. 80% were transported by air by 9 different agencies. DIDO times were: 27% less than 90 min; 27% 90 to 120 min; 44% greater than 120 min. There was minimal opportunity for improvement based on: day of week, NIHSS, and treatment with alteplase. Areas for improvement include: timeliness of door to CT (x-=13 vs 35 min), time to CT read (x-=8 vs 16 min), time to alteplase (x-=48 vs 115 min), and time to transfer (x-=125 vs 148 min), time from arrival to consult with thrombectomy capable centers (x-= 53 vs 86 min), time from consult to dispatch (x-=19 vs 26 min), and time of transfer agency on scene (x-=22 vs 37 min) for metro vs rural hospitals. Conclusions: Identified causes of delays include decision to transfer and initiation of dispatch to coordinate transport. A difference in timeliness initial diagnosis and treatment of patients outside metro areas was identified. Last known well (LKW) to arrival for transferred patients revealed a need to educate sending facilities on the expanded treatment windows- only 3 patients had a LKW to arrival time greater than 4.5 hours.