Background: Military operations place injured Servicemembers at high risk for open wounds. Austere environments and initial wound contamination increase the risk for infection. Wound infections continue to cause significant morbidity among injured Servicemembers. Limited evidence suggests that early antibiotic therapy for open wounds reduces infection rates. Methods: We obtained data from the Prehospital Trauma Registry (PHTR) from January 2013 through September 2014. This database includes data from Tactical Combat Casualty Care (TCCC) cards, Department of Defense 1380 forms, and after-action reports to provide near-real-time feedback to units on prehospital medical care. We evaluated whether patients with open wounds received antibiotics in accordance with TCCC guidelines. Low adherence was defined at less than 80%. Results: In this data set, overall, prefixed facility providers administered antibiotics to 54.0% of patients with an open combat wound. Of the antibiotics given, 11.1% were within TCCC guidelines. The relatively low administration and adherence rates persisted across subgroup analyses. Conclusion: Overall, relatively few patients with open combat wounds receive antibiotic administration as recommended by TCCC guidelines. In the group that received antibiotics, few received the specific antibiotics recommended by TCCC guidelines. The development of strategies to improve adherence to these TCCC recommendations is a research priority.