The objective of this cross-sectional study was to assess group differences between veterans with and without posttraumatic stress disorder (PTSD) in mindful awareness and mindful non-judging. The relationships between mindfulness and PTSD symptom clusters were also evaluated. Three age and gender-matched groups, (1) 15 combat veterans with PTSD, (2) 15 combat veterans without PTSD, and (3) 15 non-combat veterans without PTSD, completed the Mindful Attention Awareness Scale and the Accept without Judgment Scale. PTSD status was determined with the Clinician Administered PTSD Scale and excluded disorders screened with the Structured Clinical Interview for DSM-IV. Mindfulness scale group differences were assessed with analysis of variance. Mindfulness and the PTSD symptom clusters relationships were assessed with hierarchical regression analysis. There were group differences on mindful non-judging (F(2,44) = 7.22, p = .002) but not mindful awareness (p > .05). Combat exposure accounted for significant variation in PTSD symptoms (hyper-arousal 47%; numbing-avoiding 32%; re-experiencing 23%). Mindfulness accounted for a significant percentage variance of PTSD symptoms (re-experiencing 32%; numbing-avoiding 19%, hyper-arousal 16%), beyond combat exposure effects, although only mindful non-judging was significant in the model. This study confirms in a clinical sample that mindful non-judging is associated with PTSD symptoms and could represent a meaningful focus for treatment.