Aims: To estimate the prevalence of the metabolic syndrome among Greenland Inuit according to the World Health Organization (WHO) definition and the definition suggested by the National Cholesterol Education Program (NCEP). Methods: From 1999 to 2001, 917 adult Inuit participated in a health survey in Greenland. The examination included a 75-g oral glucose tolerance test (OGTT). Body mass index (BMI), waist circumference, waist-to-hip ratio and blood pressure were measured. Plasma glucose, serum insulin, lipids and urine albumin/creatinine ratio were measured. The metabolic syndrome was diagnosed according to the WHO criteria 1999 and to the working definition suggested by the NCEP 2001. Results: Using the WHO and the NCEP criteria, 20.7% and 17.9% of the participants had the metabolic syndrome, respectively. There was a moderate agreement between the two definitions, κ = 0.56 (95% CI 0.51-0.61). Of those with the WHO metabolic syndrome, 37.9% did not have the NCEP syndrome, and 28.5% of those with the NCEP syndrome were not classified with the metabolic syndrome under the WHO criteria. Compared with the WHO syndrome, men with the NCEP syndrome had higher mean values of waist circumference, BMI and triglycerides, and lower mean values of high-density lipoprotein (HDL) cholesterol; among women, triglycerides were higher with the NCEP syndrome. Conclusion: The metabolic syndrome is common among Inuit using either the WHO definition or the proposed NCEP definition. The classification disagreement is considerable and a universally accepted definition is needed.