Post-traumatic stress disorder (PTSD) may be a risk factor for Parkinsons disease (PD). We examined the relation between PTSD and PD in a cohort of 158,122 Veterans who had any Veterans Health Administration (VHA) or Medicare health care utilization between 10/1/1999- 2/17/2021. Using a nested case-control design we matched 10 controls to each Veteran with PD by sex, race, and rank. In conditional logistic regression models adjusted for camp and smoking, a PTSD diagnosis was significantly associated with PD (OR = 1.35; p = 0.0002); odds were higher if PTSD was coded before PD (OR = 1.53, p < 0.0001). PTSD may be a risk factor for PD.