Decreased heart rate variability (HRV) occurs with physical and psychological disorders and is a predictor of cardiac and all-cause mortality. This study was the first of which we are aware to examine and report the relationship between military sexual trauma (MST) and HRV measures. In a historical cohort study of female veterans with (n = 27) and without (n = 99) MST who received Holter and electrocardiogram evaluation at a Veteran Affairs medical center during 2007-2010, we examined the relationship between MST and the standard deviation of all R-R intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent R-R intervals (RMSSD). Female veterans with MST were younger, p = .002, frequently had a probable posttraumatic stress disorder diagnosis, 80% versus 15%, p = < .0001, and had lower SDNN, p = .0001, and RMSSD, p = .001, than those without MST. The SDNN and RMSSD of a 25-year-old female veteran with MST were comparable to that of female veterans aged 69 to 81 years without MST. Further research is needed to evaluate relationships between MST and HRV measures. © 2013 International Society for Traumatic Stress Studies.