Post-traumatic stress disorder (PTSD) is increasingly understood to be a medical disorder characterised by particular psychobiological dysfunctions that respond to specific treatments. Paroxetine is a selective serotonin re-uptake inhibitor that has been found effective in the treatment of major depression as well as a range of anxiety disorders. This paper reviews data on the use of paroxetine for the treatment of adult PTSD. There have been three 12-week, placebo-controlled studies of paroxetine in PTSD. As these followed a partly similar design, a pooled analysis of the studies is possible and is reported here. Paroxetine is effective in the short-term treatment of PTSD, resulting in significantly better response and remission rates than placebo, improving sleep disturbance and reducing each of the symptom clusters of PTSD, as well as the disability associated with this condition. The medication is effective in both male and female PTSD patients and whether or not there are comorbid disorders such as depression.