Elevated psychophysiological parameters and heightened physiological reactivity to trauma-related cues are acquired changes following trauma exposure. Measuring improvement in these variables is an appropriate evaluation of outcome in treatment studies. Heart Rate Variability (HRV) is a computerized measure of physiological responsivity derived from Holter ECG recording. Four female outpatients with persistent post-traumatic symptoms and personal impairment following “small t” trauma exposure underwent a course of EMDR treatment and were assessed at baseline, end of treatment, day 30 and day 90 of follow-up, using self-report symptom scales and 90-min Holter ECG recordings. Symptom scores decreased between baseline and end of treatment, with improvement maintained at follow-up. Several HRV measures changed favorably in different recording intervals. HRV is a feasible and sensitive method to measure physiological changes in the treatment of individuals distressed by “small t” trauma. Further investigation is advisable to expand these preliminary data.