The number of cases of the metabolic syndrome is increasing dramatically in Western countries. However, the evaluation of the metabolic syndrome is limited in Asian countries. Thus, our objectives were: 1) to investigate parameters of the metabolic syndrome defined by the National Cholesterol Education Program (NCEP)-Adult Treatment Panel III (ATPIII) in the subjects representing Korean general population and 2) the modification of which factor is most effective in reducing the metabolic syndrome. A total of 10,044 (5024 rural and 5020 urban) Korean men and women in the age range 40-69 yr voluntarily participated in this community-based cross-sectional study (a rural and an urban community was selected). Anthropometric parameters (weight, height, waist and hip circumference and blood pressure), social factors (smoking, alcohol, exercise and education status) as well as biochemical parameters (fasting glucose and insulin, lipids and body composition) were measured. Twenty-six point one per cent of the total subjects were classified as having the metabolic syndrome. Age- and sex-adjusted prevalences were 29.3 and 22.3% in the rural and urban community, respectively (p< 0.01). Abdominal obesity (46.9%) and high blood pressure (45.2%) were major components in the rural community; hypertriglyceridemia (37.6%) and low HDL-cholesterolemia (37.0%) in the urban community. In conclusion, abdominal obesity in the rural community and dyslipidemia in the urban community should be a main subject of intervention, aimed at reducing the prevalence of the metabolic syndrome in Korea. Given the rapid progression of the Korean economy over the past 30 yr, the prevalence of the metabolic syndrome is expected to increase continuously. A strategy to prevent this expected extraordinary event should be conducted at a national level.