Metabolic syndrome (MetS) is a clustering of cardiovascular risk factors characterizing central obesity, insulin resistance, dyslipidemia and high blood pressure. The concept of MetS represents the pre-cardiovascular and pre-diabetic pathologic conditions, which has been a useful tool in prognosing the development of cardiovascular disease and diabetes mellitus. Importantly, interventions applied at the pre-pathologic stage with MetS would be of great clinical and health significance in achieving better preventive and therapeutic outcomes. Yoga, a mind-body exercise, has been suggested to have beneficial effects on dyslipidemia, hypertension and diabetes. A pilot study has demonstrated the trends in the improvement of metabolic parameters in middle-aged adults with MetS but the findings are inconclusive because of the small sample size and brief yoga follow-up period (i.e., 2-month). In addition to the needs of a better designed randomized controlled trial in studying the beneficial effect of yoga in controlling MetS in middle-aged individuals, the investigation on yoga and MetS in elderly population has been lacking. This is important as the potential use of yoga as lifestyle modification in elderly individuals with MetS will result in significant reduction of the prevalence of cardiovascular disease and diabetes. Thus, this study aims to examine the efficacy of yoga exercise in improving metabolic abnormalities in middle-aged and older adults with MetS. In addition to elderly, middle-aged adults are included in the present investigation because of the idea that cardiovascular diseases and diabetes with aging can be mostly prevented by intervention at the middle-age. A randomized controlled trial with repeated measure design will be conducted to examine the effect of 1-year regular yoga training on the MetS parameters in middle-aged and older individuals who are 30-60 and 60-80 years of age, respectively. Primary outcome measures include waist circumference, systolic/diastolic blood pressure, blood glucose, triglyceride, and lipid cholesterol profile whereas secondary outcome measures include self-reported stress and depression levels. This study is anticipated to provide valuable information in exploring the therapeutic role of yoga in managing MetS. As yoga exercise is an economical regimen which can be easily and readily applied to large scale of target population, it is of hope to be practically useful to relieve the burden on cardiovascular disease and diabetes by introducing yoga lifestyle to the management of MetS.