INTRODUCTION: PTSD is associated with comprehensive disruption of several neurobiological regulation mechanisms and with a disruption in the parasympathetic-sympathetic balance. This can be measured with the heart rate variability (HRV). METHODS: A systematic review in PubMed using the keywords "hrv" or "heart rate variability" and "PTSD" or "posttraumatic stress disorder" was performed. RESULTS: Overall 15 original studies were identified. In most cases a significant relationship of PTSD for reduction of HRV was demonstrated (9 studies) or, respectively, a reduction by trends was shown in 3 studies. Limitations were discussed. DISCUSSION: In spite of the limitations, most of the studies have shown a relationship between PTSD and HRV. However, an assessment of this potential marker as a supplement for clinical diagnosis and therapy follow-up in patients with PTSD seems to be premature on the basis of the data obtained so far. Further research is required.