OBJECTIVE: Little information is available on how impaired masticatory performance relates to heart-rate variability (HRV). The aim of this study was to investigate the relationship between HRV indices and masticatory performance. MATERIALS AND METHODS: Sixty-five subjects (19 men and 46 women, 66.1 +/- 9.9 years old) who had received periodontal maintenance care at the Clinic of Preventive Dentistry of Okayama University Hospital were selected for the study. All subjects completed written questionnaires, a chewing (colour-changing gum) test for masticatory performance and measurement of occlusal force and HRV as well as oral examination. RESULTS: The high sympathetic activity (LF >/= 49.6) group showed a significantly lower level of masticatory performance (a* value) than the low sympathetic activity group (p < 0.05). There were also significant correlations of masticatory performance with LF and LF/HF (p < 0.05). CONCLUSION: These findings suggest that there is relationship between masticatory performance and HRV indices and impaired masticatory performance may be a risk factor for inducing high sympathetic activity.