This prospective descriptive study sought to determine specific genetic factors to enable pre-exposure screening of military personnel most at risk of developing post-traumatic stress disorder (PTSD). Participants are active-duty service members at Fort Hood in the United States, preparing for deployment to Iraq or Afghanistan. The mean age of the sample was 27.2 years, and 91.2% were male. The ethnicity of the sample was 80.2% not Hispanic or Latino, 18.6% Hispanic or Latino, and 1.2% not reported. The racial breakdown was 64.1% Caucasian, 15.2% African American, 2.3% American Indian/Alaskan Native, 2.1% Asian, 1.7% Native Hawaiian or Other Pacific Islander, 12.3% other, and 2.3% not reported.