BACKGROUND: Nerve injuries from gunshot wounds (GSWs) to the upper arm can cause significant morbidity and loss of function. However, indications for surgical exploration and nerve reconstruction remain unclear as both low- and high-grade injuries can present with an abnormal neurological examination. METHODS: Adult patients presenting with a history of isolated GSW to the upper arm between 2010 and 2019 at a single urban level 1 trauma center were screened for inclusion in this retrospective study. Patient demographics, neurological examination findings, concurrent injuries, and intraoperative findings were gathered. Bivariate analysis was performed to characterize factors associated with nerve injuries. RESULTS: There were 139 adult patients with isolated brachial GSWs, and 49 patients (35%) presented with an abnormal neurological examination and significantly associated with concurrent humerus fractures (39% vs 21%, CONCLUSION: Nerve injury from upper arm GSWs is common with directly traumatized nerves confirmed in at least 39% and nerve transection in at least 16% of patients with an abnormal neurological examination. Timely referral to a hand and/or peripheral nerve surgeon for close clinical follow-up, appropriate diagnosis, and any necessary surgical reconstruction with nerve grafts, tendon transfers, and nerve transfers is recommended.