BACKGROUND: Normative values for heart rate variability (HRV) measures from 10-s electrocardiograms (ECG) have not been defined. METHODS: We reported borderline abnormal (<5th percentile) and abnormal (<2nd percentile) values of standard deviation of all normal-to-normal R-R intervals (SDNN) and root mean square of successive differences between normal-to-normal R-R intervals (rMSSD) from 10-s ECGs in 1175 participants (mean age=59+/-10; 59% female; 47% white) >/=45years of age from the Multi-Ethnic Study of Atherosclerosis (MESA) who were free of cardiovascular disease (CVD) and CVD risk factors. We validated the prognostic significance of these measures in a subset of the MESA cohort with complete data. RESULTS: Borderline abnormal and abnormal SDNN and rMSSD varied by sex and race. Borderline abnormal and abnormal SDNN and rMSSD were associated with an increased risk of CVD and all-cause mortality. CONCLUSIONS: The references ranges provided in this report will guide future research using these common HRV parameters.