Patients randomized to carvedilol will be administered doses ranging from 6.25 to 15.625 mg/day using a flexible-dosing model. After a 1 week titration, investigators my increase daily dose by 6.25 mg/day at weeks 1 and 2 for a maximum dose of 15.625 mg/day. Weeks 3-4 will patients will remain on a stable, tolerable dose. At week 5 patients will have a 1 week taper.

Patients randomized to placebo will follow same dosing guidelines as if they were in the active comparator arm, carvedilol.

Oral, twice daily dosing using 3.125 mg tablets.

1 week titration (6.25 mg/day)prior to a 3 week flexible dosing option ranging from 6.25 mg/day to 15.625 mg/day followed by a 1 week taper (6.25 mg/day).

The DTS is a 17-item self report measure to assess the 17 DMS-IV symptoms of PTSD. Respondants are asked to identify the trauma that is most disturbing to them and to rate, in the past week, how much trouble they hav had with each symptom. The DTS can be used to make a preliminatry determination about whether the symptoms meet DSM criteria for PTSD, or scores can be calculated for each of the 3 PTSD symptom clusters.

The DTS will be assessed at each study visit (visit 1, 2, 3, 4, 5, 6 and 7). The primary efficacy outcome will be change from baseline (visit 2) to week 5 (visit 7).

The CAPS was developed at the National Center for PTSD and has become the "gold standard" for assessing Post Traumatic Stress Disorder. It is a user-friendly structured interview for screening, differential diagnosis, comfirming PTSD diagnosis or identifying Acute Stress Disorder.

The CAPS will be assessed at the screening visit and again at week 5 (vist 7). Change scores (from screening to week 5) will be secondary efficacy measures.