Given the central role that hippocampal deficits play in PTSD (Woon et al. 2010), and the aforementioned association between the DRD2 Taq1A polymorphism and PTSD symptoms, the aim of the present study was to explore whether the DRD2 Taq1A polymorphism moderated the association between PTSD symptoms and hippocampal volume at the subfield level. Here, DRD2 is linked to post-traumatic stress disorder.