In the current study, we aim to investigate whether post-traumatic stress disorder (PTSD) is associated with structural alterations in specific subfields of hippocampus comparing with trauma-exposed control (TC) in a relatively large sample. We included 67 PTSD patients who were diagnosed under Diagnostic and Statistical Manual of Mental Disorders (4th Edition) (DSM-Ⅳ) criteria and 78 age- and sex-matched non-PTSD adult survivors who experienced similar stressors. High resolution T1 weighted images were obtained via a GE 3.0 T scanner. The structural data was automatically segmented using FreeSurfer software, and volume of whole hippocampus and subfield including CA1, CA2-3, CA4-DG, fimbria, presubiculum, subiculum and fissure were extracted. Volume differences between the two groups were statistically compared with age, years of education, duration from the events and intracranial volume (ICV) as covariates. Hemisphere, sex and diagnosis were entered as fixed factors. Relationship between morphometric measurements with Clinician-Administered PTSD Scale (CAPS) score and illness duration were performed using Pearson’s correlation with SPSS. Comparing to TC, PTSD patients showed no statistically significant alteration in volumes of the whole hippocampus and all the subfields (P > 0.05). In male patients, there were significant correlations between CAPS score and volume of right CA2-3 ( R2 = 0.197, P = 0.034), right subiculum (R2 = 0.245, P = 0.016), and duration statistically correlated with right fissure (R2 = 0.247, P = 0.016). In female patients, CAPS scores significant correlated with volume of left presubiculum (R2 = 0.095, P = 0.042), left subiculum (R2 = 0.090, P = 0.048), and left CA4-DG (R2 = 0.099, P = 0.037). The main findings of the current study suggest that stress event causes non-selective damage to hippocampus in both PTSD patients and TC, and gender-specific lateralization may underlie PTSD pathology.