Objective. The mismatch negativity (MMN) component of the event-related brain potential has been used to examine auditory monitoring in various mental disorders. Previous research with posttraumatic stress disorder (PTSD) patients has revealed contradictory results. Enhanced as well as diminished MMNs have been obtained. Method. The multifeature protocol was employed to investigate the pattern of MMN in 17 military deployment–related PTSD patients and a group of healthy university student controls. Results. Our results suggest no general effect of PTSD on the MMN involving the majority of acoustic features. There were slightly reduced MMNs in patients relative to controls for 2 of the features (duration, location). On the other hand, the N1 component was reduced in patients compared with controls. Conclusions. Choice of the stimulus protocol might be an important factor to explain inconsistent results in previous research. Differences in the auditory context between stimulus protocols and deficits in the formation of larger (auditory) contexts in PTSD might account for the results. Significance. This study adds to the small number of studies on PTSD and MMN and revealed valuable information to guide future, related studies. © EEG and Clinical Neuroscience Society (ECNS) 2018.