Posttraumatic stress symptoms (PTSS) are associated with significant distress and impairment. Research has therefore focused on identifying neurobehavioral deficits that contribute to the pathophysiology of PTSS. One issue that has contributed to difficulty in identifying these deficits is the highly heterogeneous nature of PTSS. PTSS is comprised of four, factor analytically distinct dimensions of symptoms - re-experiencing, avoidance, hyperarousal, and negative cognitions and mood. It is therefore unlikely that there is one single mechanism that accounts for all of PTSS and elucidating neurobehavioral deficits associated with specific PTSS symptom dimensions may better inform clinical prevention and intervention efforts. Within the broader internalizing disorder literature, two key constructs that contribute to psychopathology are aberrant neural reactivity to threat and reward. However, the literature linking PTSS to these deficits is mixed, suggesting that aberrant neural reactivity to threat or reward may be specific to certain PTSS dimensions. In a sample of 51 trauma-exposed adults with a range PTSS, the present study therefore examined how the four dimensions of PTSS uniquely relate to two well-validated event-related potential (ERP) neural indices of threat and reward reactivity - the error-related negativity (ERN) and reward-related positivity (RewP), respectively. Results indicated that hyperarousal symptoms were associated with enhanced ERN, and enhanced RewP. In contrast, negative cognitions and mood symptoms were uniquely associated with a more blunted RewP. These results indicate that certain PTSS symptom dimensions have unique relations with neural indicators of threat and reward reactivity and may therefore have distinct pathophysiologies.