To assess the prevalence of the metabolic syndrome disease cluster in the Hong Kong Chinese population we applied the US National Cholesterol Education Programme Adult Treatment Panel III (NCEP ATP III) guidelines. This was present if > or =3 of the following conditions were present: Hypertension (> or =130/85 mmHg); fasting plasma glucose was > or =6.1 mmol/L; fasting plasma triglycerides > or =1.69 mmol/L; fasting HDL-cholesterol <1.04 or <1.29 mmol in males and females, respectively; or subjects were receiving treatment for their condition; waist circumference >88 or 102 cm (Asian WHO criteria > or =80 or 90 cm) in females and males, respectively. A total of 16.7% (17.1 (95%CI 15.7-18.5)% age and gender-adjusted) of the 2893 subjects had the metabolic syndrome. The prevalence of having at least 2, 3, 4 or 5 components was 34.5, 16.7, 6.4 and 1.4%, respectively. The prevalence increased from 3.1% in those aged 25-29 years to 41.0% in those aged over 70 years. Using the 2001 Census, 880,499 Hong Kong residents would have the metabolic syndrome. If the WHO recommended waist circumference for Asians is used, the age and gender-adjusted prevalence is significantly higher at 21.2% (21.9 (95%CI 20.4-23.4)%). In summary, the high prevalence of the metabolic syndrome in adult Hong Kong Chinese, particularly in the elderly, forewarns a rapidly increasing problem in Mainland China, and other Asian populations, which may have overwhelming public health ramifications.