OBJECTIVE:To evaluate reproducibility (reliability and agreement) of the Brachial Assessment Tool (BrAT), a new patient-reported outcome measure for adults with traumatic brachial plexus injury (BPI). DESIGN:Prospective repeated-measure design. SETTING:Outpatient clinics. PARTICIPANTS:Adults with confirmed traumatic BPI (N=43; age range, 19-82y). INTERVENTIONS:People with BPI completed the 31-item 4-response BrAT twice, 2 weeks apart. Results for the 3 subscales and summed score were compared at time 1 and time 2 to determine reliability, including systematic differences using paired t tests, test retest using intraclass correlation coefficient model 1,1 (ICC1,1), and internal consistency using Cronbach α. Agreement parameters included standard error of measurement, minimal detectable change, and limits of agreement. MAIN OUTCOME MEASURE:BrAT. RESULTS:Test-retest reliability was excellent (ICC1,1=.90-.97). Internal consistency was high (Cronbach α=.90-.98). Measurement error was relatively low (standard error of measurement range, 3.1-8.8). A change of >4 for subscale 1, >6 for subscale 2, >4 for subscale 3, and >10 for the summed score is indicative of change over and above measurement error. Limits of agreement ranged from ±4.4 (subscale 3) to 11.61 (summed score). CONCLUSIONS:These findings support the use of the BrAT as a reproducible patient-reported outcome measure for adults with traumatic BPI with evidence of appropriate reliability and agreement for both individual and group comparisons. Further psychometric testing is required to establish the construct validity and responsiveness of the BrAT.