Objective To understand the prevalence of metabolic syndrome in Gansu.Methods A multistage stratified cluster sampling method was conducted.A total of 6 609 adults (range 18-96 years old) from 5 cities located in different areas of Gansu province were included in the analyses and all of them underwent physical examinations.Metabolic syndrome was diagnosed under the modified 2005 National Cholesterol Education Program Adult Treatment Panel Ⅲ (ATP Ⅲ) guidelines as well as the 2004 Chinese Diabetes Society (CDS) guidelines.Results Using the modified ATP Ⅲ criterion for diagnosis,the unadjusted prevalence rate of metabolic syndrome was 30.43％ (35.25％ in males and 23.02％ in females,respectively) and the age-adjusted prevalence was 29.05％.The prevalence of metabolic syndrome increased with age.Combination of central obesity,high TG hyperlipidemia and low HDL-C hyperlipidemia was most frequently seen.Under the CDS criterion,the unadjusted prevalence of metabolic syndrome was 13.42％,with the age-adjusted prevalence as 12.65％.A low level of agreement between the ATP Ⅲ and CDS was observed (Kappa index=0.496).Conclusion Under the ATP Ⅲ definition,more adults with MS were identified thus could be recommended as the preferred diagnostic criterion.Metabolic syndrome had become a noteworthy public health problem.Prevention programs related to metabolic syndrome should be urgently warranted.