Using survey data, the authors assessed whether military personnel's prior mental health status would influence their likelihood of being deployed. None of the previous studies that assessed a possible "healthy warrior effect," in which persons selected for deployment have better predeployment health, were based on surveys. A sample of 2,820 United Kingdom military personnel studied in 2002, before the Iraq War, was contacted again between 2004 and 2006. The baseline questionnaire included a measure of psychological distress (the General Health Questionnaire), the PTSD [posttraumatic stress disorder] Checklist (PCL), physical symptoms, and level of medical fitness. A total of 1,885 (67%) participants completed a follow-up questionnaire. General Health Questionnaire caseness in 2002 was associated with a reduction in risk of deployment later on (risk ratio = 0.81, 95% confidence interval: 0.67, 0.99). Scoring high on the PCL intrusiveness and avoidance domains also reduced the risk of deployment. These associations were slightly stronger when the comparison was made between persons who were deployed to Iraq and those who were not. Although risk ratios were well below 1.00, PCL categories were not significantly associated with being deployed. This study demonstrated a small "healthy warrior effect"; persons with better psychological health had a higher chance of being deployed, even after adjustment for predeployment medical fitness.