The objective of this study was to evaluate the 5-year changes of aerobic capacity, fat ratio and flexibility in older Tai Chi Chuan (TCC) practitioners and sedentary controls. Sixty-nine community-dwelling elderly individuals (mean age: 68.6 +/- 6.3 years) completed this study. The TCC group (18 M; 17 F) had been practicing TCC regularly for 6.3 +/- 3.7 years at baseline and continued training in the study interval. The control group (16 M; 18 F) did not participate in any regular exercise program. A graded bicycle exercise testing was conducted at the baseline and at 5-year to evaluate the age-related decline in aerobic capacity. Triceps and subscapular skinfolds, and thoracolumbar flexibility were also measured. At baseline, the TCC group displayed higher peak oxygen uptake $({\dot{\rm V}}{\rm O}_{2{\rm peak}})$ and thoraolumbar flexibility, and lower fat ratio than the control group. At the 5-year follow-up, the TCC group displayed a smaller decrease in $\dot{\rm V}{\rm O}_{2{\rm peak}}$ than the sedentary group. The annual decrease of $\dot{\rm V}{\rm O}_{2{\rm peak}}$ in TCC men and women was 0.32 and 0.22 ml . kg(-1) . min(-1), respectively. In the control group, the annual decrease of $\dot{\rm V}{\rm O}_{2{\rm peak}}$ was 0.50 and 0.36 ml . kg(-1) . min(-1) in men and women, respectively. The TCC group also showed a smaller increase of body fat ratio, and a less decrease of flexibility than the control group. In conclusion, long-term practice of TCC attenuates the age-related decline of aerobic capacity, and it also reduces the increase of body fat ratio in older individuals. TCC may be prescribed as a conditioning exercise for the elderly to maintain their health fitness.