 Three hundred 300 male or female outpatients, over 18 years of age, will be enrolled in this study to determine whether fluoxetine can be used as a treatment for Posttraumatic Stress Disorder in soldiers recently returning from combat exposure. There will be two phases to the study. In Phase I Fluoxetine usual psychological care will be compared with Placebo usual psychological care over a 12-week period. Subsequently, in Phase II all subjects will be offered the opportunity to enroll in a 20-week open-label trial on Fluoxetine. If response is inadequate, adjunctive treatment with either buspirone or bupropion will be offered. The investigational drugs are Fluoxetine, Buspirone and Bupropion. All are commercially available. 