Military-related posttraumatic stress disorder (PTSD) is a significant psychiatric condition associated with severe psychosocial dysfunction. This study examined the predictors of treatment outcome in a group of veterans with military-related PTSD. Participants were 102 Canadian combat and peacekeeping veterans who received treatment at a specialized outpatient clinic for veterans with psychiatric disorders resulting from military operation. Analysis demonstrated a significant decrease in PTSD severity during the 1-year period (Yuan-Bentler χ2 [86, N = 99] = 282.45, p < 0.001). We did not find chronicity, alcohol use, and anxiety or depression severity as significant predictors for PTSD symptom decline. However, initial depression significantly predicted anxiety symptom decline, and initial anxiety predicted depression symptom decline. This study demonstrated that, despite considerable comorbidity, significant treatment gains, including remission of PTSD, can be achieved in an outpatient setting in veterans with chronic military-related PTSD.