OBJECTIVE: The aim of the present study was to develop reference data for the Iranian population for anthropometric values and cardiometabolic data in comparison with those in Americans, as representative of a Western population. DESIGN: The present cross-sectional survey, conducted as part of the baseline survey of a community-based interventional study (the Isfahan Healthy Heart Programme), used a two-stage clustering design and was conducted in 12 600 randomly selected adults (> or =19 years of age) and 2000 adolescents (aged 11-18 years) living in three cities in the central part of Iran. For comparison with a Western population, comparable data for Americans were derived from the data sets of the Second and Third National Health and Nutrition Examination Surveys (NHANES II and NHANES III). RESULTS: Iranian women had significantly higher mean BMI, waist circumference (WC), hip circumference (HC) and waist:hip ratio (WHR) than Iranian men and American women; but the mean BMI of Iranian men was lower than that of American men. The mean serum TAG level of Iranian men was significantly higher than that of Iranian women, whereas the mean serum total cholesterol (TC), LDL cholesterol (LDL-C) and HDL cholesterol (HDL-C) levels were significantly higher in Iranian women than in men. The Iranian population had lower mean TC, LDL-C and TAG levels than the Americans, but such difference was not documented for HDL-C. Iranian adolescents had significantly lower mean BMI and higher mean TAG than did American adolescents. CONCLUSIONS: Our findings provide serious evidence for health professionals and policy makers about the very high prevalence of generalized and abdominal obesity in Iran. Controlling this emerging health problem, notably in women, should become a national priority in Iran and necessitates comprehensive public health programmes.