BACKGROUND: The prevalence of obesity is increasing in Korea, including rural areas. We examined the changes in the prevalence of metabolic syndrome (MetS), defined by revised National Cholesterol Education Program (NCEP) or International Diabetes Federation (IDF) criteria, in a rural area of Korea during the past 6 years. METHODS: A total of 1,119 subjects (424 men and 695 women) aged > or = 30 years were initially recruited in 1997. Baseline clinical data and various laboratory values were obtained. Six years later, we performed a follow-up study in 814 subjects (316 men and 498 women) of which 558 were original participants and 256 subjects were new. The prevalence of MetS was assessed by the criteria of NCEP or IDF. RESULTS: The prevalence of central obesity and impaired fasting glucose increased in both sexes during the period between 1997 and 2003. The prevalence of MetS according to the IDF criteria also increased. In men, the age-adjusted prevalence of MetS was 10.9% in 1997 and 23.3% in 2003. In women, it was 42.2% in 1997 and 43.4% in 2003. However, the prevalence of MetS according to the NCEP criteria increased only in men. CONCLUSION: There have been increases in the prevalence of central obesity and MetS according to the IDF criteria during the recent 6 years in a rural area of Korea.