Background: Transient symptoms with infarction (TSI) is distinguished from transient ischemic attack (TIA) by the presence of diffusion-weighted imaging (DWI) lesions on MRI. We report a series of patients with DWI lesions identified in an emergency department observation unit (EDOU) TIA protocol. Methods: Patients were treated in the ED of a tertiary care center (annual census=100,000 visits). In the first 3 months of operation of an EDOU for TIA, 50 patients met inclusion criteria of sudden/transient neurological deficit in the absence of known metabolic or cardiac source. Patients were excluded from the study if they demonstrated: persistent or stuttering deficits; fever >100.4F, heart rate <60 or >100 bpm; SBP >180 or <100mmHg; pulse ox <93%; or positive CT. Evaluation included: laboratory analyses; CT/MRI/MRA of the head/neck; EKG; echocardiogram, and neurology consult. MR data (ED 1.5T MR unit) include: DWI, ADC, GRE, and T2FLAIR images. Patients with TSI, were identified by the presence of 1 or more DWI bright and ADC dark lesions on ED MRI. All patients completed CT and MR imaging within < 24 hours of admission. This study was approved by the hospital IRB. Results: TSI was identified in 10/50 EDOU patients (Mdn age 72.5, ABCD2 score 5). Two patients demonstrated infarcts in multiple vascular territories. Table 1 illustrates patient demographics, comorbidities, presentations, and outcome. Fifty percent of TSI patients were admitted from EDOU, 3 patients returned to the ED within 30 days , and no 30 day distinct recurrent events, such as recurrent stroke were identified. Conclusions: EDOU for TIA including DW-MRI resulted in TSI diagnosis in 20% of patients. In the TSI cases identified, infarct locations were heterogeneous; vascular and/or cardiac etiology must be considered. Longitudinal analysis is recommended to further assess the relationship between presentation, TSI risk, risk of recurrent stroke, and need for hospital admission.