The optimal approach to prehospital care of trauma patients is controversial, and thought to require balancing advanced field interventions with rapid transport to definitive care. We sought principally to examine any association between the amount of prehospital IV fluid (IVF) administered and mortality. We conducted a retrospective cohort analysis of trauma registry data patients who sustained penetrating trauma between January 2008 and February 2011, as identified in the Pennsylvania Trauma Systems Foundation registry with corresponding prehospital records from the Philadelphia Fire Department. Analyses were conducted with logistic regression models and instrumental variable analysis, adjusted for injury severity using scene vital signs before the intervention was delivered. There were 1966 patients identified. Overall mortality was 22.60%. Approximately two-thirds received fluids and one-third did not. Both cohorts had similar Trauma and Injury Severity Score-predicted mortality. Mortality was similar in those who received IVF (23.43%) and those who did not (21.30%) (p = 0.212). Patients who received IVF had longer mean scene times (10.82 min) than those who did not (9.18 min) (p < 0.0001), although call times were similar in those who received IVF (24.14 min) and those who did not (23.83 min) (p = 0.637). Adjusted analysis of 1722 patients demonstrated no benefit or harm associated with prehospital fluid (odds ratio [OR] 0.905, 95% confidence interval [CI] 0.47-1.75). Instrumental variable analysis utilizing variations in use of IVF across different Emergency Medical Services (EMS) units also found no association between the unit's percentage of patients that were provided fluids and mortality (OR 1.02, 95% CI 0.96-1.08). We found no significant difference in mortality or EMS call time between patients who did or did not receive prehospital IVF after penetrating trauma. Published by Elsevier Inc.