Introduction: Post-traumatic stress disorder (PTSD) is a form of anxiety disorders. PTSD typically follows an exposure to severe stress. It is characterized by a particular clinical syndrome, including re-experiencing symptoms and alterations in arousal, avoidance, cognition, and mood conditions. Recent evidences propose that micro-RNAs are crucial epigenetic players in mental disorders. It has been demonstrated that micro-RNAs are promising non-invasive biomarkers for different mental health disorders. It has been reported that the levels of micro-RNAs have been changed in psychotic diseases, including Alzheimer's disease and PTSD. Conclusion: Micro-RNAs seem to play a role in pathophysiology of psychological diseases. In this article, we discussed the new findings suggesting a relationship between micro-RNAs and PTSD as well as the possible roles of micro-RNAs in diagnosis and treatment of this mental disorder.