Purpose: The purpose of this study was to test the effects of the Tai Chi exercise on metabolic syndrome and health-related quality of life in middle-aged women. Methods: A quasi-experimental design was used. Subjects were sixty middle-aged women with metabolic syndrome. All of the subjects were met the criteria of the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III). The subjects were divided into the experiment group (n=33) trained the Tai Chi for 12 weeks and the control group (n=27). Metabolic syndrome risk factors including blood pressure, waist circumference, glucose, triglyceride (TG), and high density lipoprotein cholesterol (HDL-C) were measured before and after the 12-week period. Euro Quality of Life Questionnaire 5-Dimensional Classification (EQ-5D) was used to evaluate the health-related quality of life. Results: The experiment group showed significant decreases in diastolic blood pressure, waist circumference, glucose, and TG; and increase in HDL-C compared to the control group. For the health-related quality of life evaluation, the experiment group showed significant improvement more than the control group. Conclusion: The Tai Chi exercise may be effective intervention in preventing cardiovascular disease caused by metabolic syndrome in middle-aged women.