This study examines relationships among military sexual trauma (MST), nonmilitary sexual trauma, and posttraumatic stress disorder (PTSD). A sample of 196 female veterans was assessed for trauma occurring before, during, and after military service, and for current PTSD. The prevalence of MST was higher than that of premilitary and postmilitary sexual trauma. Premilitary trauma did not significantly increase the odds of experiencing MST, but did increase the odds of experiencing postmilitary sexual trauma. Logistic regression analyses revealed MST was more strongly associated with PTSD than was premilitary or postmilitary trauma. Women with MST had the greatest increased odds of developing PTSD. Understanding risk factors for and taking steps to prevent MST may reduce cases of PTSD in female veterans.