PURPOSE: to compare the effects of a short style of Tai Chi versus brisk walking training programme on aerobic capacity, heart rate variability (HRV), strength, flexibility, balance, psychological status and quality of life in elderly women. METHODS: nineteen community-dwelling, sedentary women (aged 71.4 +/- 4.5 years) were randomly assigned to Tai Chi Chuan (TCC; n = 11) or brisk walking group (BWG; n = 8). A separate group of elderly women was recruited from the same population to act as a sedentary comparison group (SCG; n = 8). The exercise groups met for 1 h, three days per week for 12 weeks. Outcomes measured before and after training included estimated VO2max, spectral analysis of HRV (high-frequency, low-frequency power as well as high- and low-frequency power in normalised units) as a measure of autonomic control of the heart, isometric knee extension and handgrip muscle strength, single-leg stance time, the State Trait Anxiety Inventory (STAI), Profile of Mood States (POMS) and Short Form-36 (SF-36) questionnaires. RESULTS: significant improvement was seen in estimated VO(2)max in the TCC group (TCC versus SCG P = 0.003, TCC versus BWG P = 0.08). The mean within-person change of high-frequency power in normalised units (HFnu) increased [8.2 (0.14-16.3)], representing increased parasympathetic activity, and low-frequency power in normalised units (LFnu) decreased [-8.7 (-16.8-0.5)], representing decreased sympathetic activity, in the TCC group only. Significant gains were also seen in the non-dominant knee extensor strength and single-leg stance time (TCC versus BWG P < 0.05). CONCLUSIONS: a short style of TCC was found to be an effective way to improve many fitness measures in elderly women over a 3-month period. TCC was also found to be significantly better than brisk walking in enhancing certain measures of fitness including lower extremity strength, balance and flexibility.