1. This study examines the relation between baseline clinical characteristics in patients with posttraumatic stress disorder (PTSD) and response to treatment with a reversible monoamine oxidase A inhibitor (RIMA), brofaromine. 2. Data from two comparable, double-blind, placebo-controlled studies of brofaromine in patients with PTSD were combined. Bivariate analyses of variables of interest and outcome were performed. 3. Treatment response was significantly associated with lower baseline scores on the full scale Clinician-Administered PTSD Scale (CAPS) and on CAPS subscales B (re-experiencing) and C (avoidance/numbing), as well as to drug treatment with brofaromine. Placebo response was related to a history of past sexual trauma. 4. Brofaromine may have therapeutic benefit in treating PTSD, with lower baseline levels of reexperiencing and avoidance/numbing and overall less severe PTSD most predictive of outcome.