Introduction: Many military service members with PTSD do not receive evidence-based specialty behavioral health treatment because of perceived barriers and stigma. Behavioral health providers in primary care can deliver brief, effective treatments expanding access and reducing barriers and stigma. The purpose of this randomized clinical trial was to determine if a brief cognitive-behavior therapy delivered in primary care using the Primary Care Behavioral Health model would be effective at reducing PTSD and co-occurring symptoms. Method: A total of 67 service members (50 men, 17 women) were randomized to receive a brief, trauma-focused intervention developed for the primary care setting called Prolonged Exposure for Primary Care (PE-PC) or a delayed treatment minimal contact control condition. Inclusion criteria were significant PTSD symptoms following military deployment, medication stability, and interest in receiving treatment for PTSD symptoms in primary care. Exclusion criteria were moderate or greater risk of suicide, severe brain injury, or alcohol/substance use at a level that required immediate treatment. Assessments were completed at baseline, posttreatment/postminimal contact control, and at 8-week and 6-month posttreatment follow-up points. Primary measures were the PTSD Symptom Scale-Interview and the PTSD Checklist—Stressor-Specific. Results: PE-PC resulted in larger reduction in PTSD severity and general distress than the minimal contact control. Delayed treatment evidenced medium to large effects comparable to the immediate intervention group. Treatment benefits persisted through the 6-month follow-up of the study. Discussion: PE-PC delivered in integrated primary care is effective for the treatment of PTSD and co-occurring symptoms and may help reduce barriers and stigma found in specialty care settings.