OBJECTIVE: To assess the characteristics of autonomic control of heart rate in postmenopausal women before and after hormone replacement therapy (HRT). METHODS: Time domain and spectral domain heart rate variability (HRV) were performed in 58 postmenopausal women before and after HRT. RESULTS: Compared with examinations at baseline, values of all HRV measurements in subjects given HRT were increased at the fourth month (P < 0.05), while they remained unchanged in the control group (P > 0.05). Results showed an inverse correlation between all measures of HRV and mean R-R interval in the treatment group. CONCLUSION: HRT reduces sympathetic drive in postmenopausal symptomatic women. HRV may be an index of imbalance of autonomic control in perimenopausal women.