OBJECTIVES: Post-traumatic stress disorder (PTSD) is a type of anxiety disorder that occurs after experiencing a traumatic event, and can lead to severe impairment of a patient's daily life. The study aims to assess the clinical and economic burden of PTSD in the U.S. veteran population. METHODS: Patients diagnosed with PTSD (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM]: 309.81) were selected from the Veterans Health Administration (VHA) database (October 1, 2006-May 31, 2010). The first observed diagnosis date was defined as the index date. Continuous medical and pharmacy benefits were required 12-months pre- and post-index date. The top ten most common comorbidities were calculated for the 12-month baseline period. The top ten treatments were calculated for 60 days post-index date. Healthcare resource utilization (inpatient, outpatient, office, emergency room [ER] visits), and costs (inpatient, outpatient, ER, pharmacy total costs) were assessed for the 12-month follow-up period. Descriptive statistics were calculated as means ± standard deviation (SD) and percentages to measure treatment, cost, and utilization distribution in the sample.  RESULTS: For VHA PTSD patients (n=488,770), the most common comorbidities were essential hypertension (19.07%) and depressive disorder (13.42%.%). 50.43% of patients were prescribed anti-depressant treatment, and 15.35% anti-cholinergics treatment. The most commonly prescribed medications were citalopram hydrobromide (17.94%), simvastatin (15.47%), omeprazole (12.26%), lisinopril (11.92%), and trazodone (11.30%). Percentages of inpatient (16.10%), ER (22.76%), physician office (99.86%), and outpatient visits (99.89%) were also calculated. Patient expenditures were found to be $5,240 (SD= $29,382) for inpatient, $264 (SD=$822) for ER, $8,437 (SD= $10,803) for physician office and $8,926 (SD=$11,443) for outpatient visits. CONCLUSIONS: Results suggest that hypertension and depressive disorder are the most common comorbidities during the baseline period. Anti-depressant prescriptions were most prevalent during the 2-month follow-up period. PTSD was associated with high inpatient and ER visit rates, translating into a high cost burden.