Heartrate variability biofeedback (HRVB) is a non-invasive treatment in which patients are assumed to self-regulate a physiological dysregulated vagal nerve. Although the therapeutic approach of HRVB is promising in various stress-related disorders, it has only been offered on a regular basis in a few mental health treatment settings.To analyse the efficacy of HRV biofeedback as an additional psychophysiological treatment for depression and PTSD.Systematic review with search terms HRV, biofeedback, PTSD, depression, panic disorder and anxiety disorder.Our search of the literature yielded 789 studies. After critical appraisal using the GRADE method, we selected 6 randomised controlled trials (RCTs) and 4 relevant studies. The RCTs with control groups 'treatment as usual' and muscle relaxation training revealed significant clinical efficacy and better results than control conditions after 4 to 8 weeks training.Although this systematic review shows the popularity of HRV in literature, it does not indicate that HRVB really has been reviewed systematically. Significant outcomes of this limited number of randomised studies indicate there may be a clinical improvement when HRVB training is integrated into treatment of PTSD and depression, particularly when this integration procedure is combined with psychotherapy. More research needs to be done with larger groups and further efforts are needed to integrate HRVB into treatment of stress-related disorders in psychiatry. Future research also needs to focus on the psychophysiological mechanisms involved.