Background and Purpose: Prehospital notification of patients with suspected acute stroke by emergency medical services (EMS) personnel is recommended to reduce delays in time-dependent management such as thrombolytic therapy. We developed ” the Brain Saver”, which is a smartphone-assisted prenotification system using mobile application platform, and evaluated preliminarily the effects of this system on improving quality indicator for thrombolysis therapy in acute ischemic stroke. Methods: Through the Brain Saver, the EMS personnel sent the clinical information, such as age, sex, time of symptom onset, expected arrival time, neurological symptom of the patient with suspected acute stroke in the field, so that the stroke team prepared to prioritize the hospital resources such as computerized tomography (CT) and various laboratory test for suspected stroke patients. On arrival at emergency room, patients were transferred directly from triage onto the CT room on the ambulance stretcher, and the stroke team meet patient. Between September 2014 and July 2015, we compared quality indicators including door-to-needle time (DNT), door-to-imaging time (DIT) of patients with intravenous tissue plasminogen activator (tPA) with prenotification to those without prenotification. Results: During study period, time of onset to arrival in patients with prenotification using the Brain Saver was similar in those without. However, compared with tPA patients who arrived without prenotification, the median (interquartile range) DNT decreased from 55 (42-92) to 36 (32-42) minutes (p=0.003) and DIT was reduced from 11 (7-15) to 3 (2-6) minutes (p<0.0001). Conclusions: The Brain Saver was the efficient tool to communicate between EMS personnel and the stroke team for the prenotification of patients with acute stroke. The prenotification improved quality indicator of in-hospital stroke management by reducing time delay in thrombolytic therapy.