IMPORTANCE: In the current health care environment with increased scrutiny and growing concern regarding opioid use and abuse, there has been a push toward greater regulation over prescriptions of opioids. Trauma patients represent a population that may be affected by this regulation, as the incidence of pain at hospital discharge is greater than 95%, and opioids are considered the first line of treatment for pain management. However, the use of opioid prescriptions in trauma patients at hospital discharge has not been explored. OBJECTIVE: To study the incidence and predictors of opioid prescription in trauma patients at discharge in a large national cohort. DESIGN, SETTING, AND PARTICIPANTS: Analysis of adult (18-64 years), opioid-naive trauma patients who were beneficiaries of Military Health Insurance (military personnel and their dependents) treated at both military health care facilities and civilian trauma centers and hospitals between January 1, 2006, and December 31, 2013, was conducted. Patients with burns, foreign body injury, toxic effects, or late complications of trauma were excluded. Prior diagnosis of trauma within 1 year and in-hospital death were also grounds for exclusion. Injury mechanism and severity, comorbid conditions, mental health disorders, and demographic factors were considered covariates. The Drug Enforcement Administration's list of scheduled narcotics was used to query opioid use. Unadjusted and adjusted logistic regression models were used to determine the predictors of opioid prescription. Data analysis was performed from June 7 to August 21, 2016. EXPOSURES: Injury mechanism and severity, comorbid conditions, mental health disorders, and demographic factors. MAIN OUTCOMES AND MEASURES: Prescription of opioid analgesics at discharge. RESULTS: Among the 33 762 patients included in the study (26 997 [80.0%] men; mean [SD] age, 32.9 [13.3] years), 18 338 (54.3%) received an opioid prescription at discharge. In risk-adjusted models, older age (45-64 vs 18-24 years: odds ratio [OR], 1.28; 95% CI, 1.13-1.44), marriage (OR, 1.26; 95% CI, 1.20-1.34), and higher Injury Severity Score (>9vs <9: OR, 1.40; 95% CI, 1.32-1.48) were associated with a higher likelihood of opioid prescription at discharge. Male sex (OR, 0.76; 95% CI, 0.69-0.83) and anxiety (OR, 0.82; 95% CI, 0.73-0.93) were associated with a decreased likelihood of opioid prescription at discharge. CONCLUSIONS AND RELEVANCE: The incidence of opioid prescription at discharge (54.3%) closely matches the incidence of moderate to severe pain in trauma patients, indicating appropriate prescribing practices. We advocate that injury severity and level of pain-not arbitrary regulations-should inform the decision to prescribe opioids.