This study evaluated the efficacy of paroxetine for symptoms and associated features of chronic posttraumatic stress disorder (PTSD), interpersonal problems, and dissociative symptoms in an urban population of mostly minority adults. Adult outpatients with a primary DSM-IV diagnosis of chronic PTSD received 1 week of single-blind placebo (N = 70). Those not rated as significantly improved were then randomly assigned to placebo (N = 27) or paroxetine (N = 25) for 10 weeks, with a flexible dosage design (maximum 60 mg by week 7). Significantly more patients treated with paroxetine were rated as responders (14/21, 66.7%) on the Clinical Global Impression-Improvement Scale (CGI-I) compared to patients treated with placebo (6/22, 27.3%). Mixed effects models showed greater reductions on the Clinician-Administered PTSD Scale (CAPS) total score (primary plus associated features of PTSD) in the paroxetine versus placebo groups. Paroxetine was also superior to placebo on reduction of dissociative symptoms [Dissociative Experiences Scale (DES) score] and reduction in self-reported interpersonal problems [Inventory of Interpersonal Problems (IIP) score]. In a 12-week maintenance phase, paroxetine response continued to improve, but placebo response did not. Paroxetine was well tolerated and superior to placebo in ameliorating the symptoms of chronic PTSD, associated features of PTSD, dissociative symptoms, and interpersonal problems in the first trial conducted primarily in minority adults.