PURPOSE: This study evaluated the effect of Tai Chi Chuan (TCC) on the autonomic nervous modulation in older persons. METHODS: Twenty TCC practitioners and 20 normal controls were included in this study. The stationary state spectral heart rate variability (HRV) measures between TCC practitioners and normal controls, and the sequential changes in HRV measures after classical Yang\'s TCC were compared. RESULTS: The total power, very low-frequency power, low-frequency power, normalized low-frequency power, and low-/high-frequency power ratios in TCC practitioners were all significantly higher than those of normal controls, whereas the heart rate and systolic and diastolic blood pressures were not different between these two groups of subjects. After TCC, the normalized high-frequency power increased significantly from 22.8 +/- 14.6 normalized units (nu) before TCC to 28.2 +/- 16.1 nu 30 min after TCC and to 30.6 +/- 18.4 nu 60 min after TCC. In contrast, the low-/high-frequency power ratio decreased significantly from 2.5 +/- 2.4 before TCC to 1.8 +/- 1.4 30 min after TCC and to 2.2 +/- 2.9 60 min after TCC. The heart rate, systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, and pulse pressure also decreased sequentially after TCC. CONCLUSION: The short-term effect of TCC was to enhance the vagal modulation and tilt the sympathovagal balance toward deceased sympathetic modulation in older persons. TCC might be good health-promoting calisthenics for older persons.