Recent reviews and meta-analyses reported structural gray matter changes in patients suffering from adult-onset posttraumatic stress disorder (PTSD) and in subjects with and without PTSD who experienced childhood trauma. However, it remains unclear if such structural changes are also affecting the white matter. The aim of this systematic review is to provide a comprehensive overview of all empirical investigations measuring white matter integrity in populations affected by PTSD and/or childhood trauma. To this end, results from different methodological approaches were included. Twenty-five articles are reviewed of which 10 pertained to pediatric PTSD and the effects of childhood trauma measured during childhood, seven to the effects of childhood trauma measured during adulthood, and eight to adult-onset PTSD. Overall, reductions in white matter volume were reported more often than increases in these populations. However, the heterogeneity of the exact locations indicates only a weak overlap across published studies. In addition, a meta-analysis was carried out on seven whole-brain diffusion tensor imaging (DTI) studies in adults. Significant clusters of both increases and decreases were identified in various structures, most notably the cingulum and the superior longitudinal fasciculus. Future research directions are discussed.