The aims of this study were: (i) to estimate the dependency between BMI and waist:height ratio (WHtR) as measures of general and abdominal adiposity, and (ii) to evaluate the influence of socio-demographic factors on both measures and on their dependency in risk classification. Data from a cross-sectional study conducted in 2009 among a representative sample of 3529 Portuguese adults were used. Height, weight and waist were measured and socio-demographic data (sex, age, education level, occupational status, marital status, region of residence) were obtained. Using logistic regression, crude and adjusted OR for high general (BMI ≥25·0 kg/m 2 ) and abdominal (WHtR ≥0·5) adiposity, and for incompatible classification between them, were calculated. Above half (50·8 %) of the respondents had high BMI and 42·1 % had high WHtR, and the rates were higher in men than in women. There was an inverse association between education level and both adiposity measures. The lowest prevalence of high general and abdominal adiposity was observed in students and singles, whereas the highest was found in retired, widowed and respondents from Azores, Madeira and Alentejo. Nearly a quarter of respondents (24·0 %) were incompatibly classified by BMI and WHtR, with higher prevalence in men than in women and in low-than in high-educated people. Future surveys should focus on developing at least sex-specific cut-offs for both measures. Implementation of effective strategies for preventing and reducing high adiposity levels in Portugal should be directed primarily to men, older, low-educated individuals, as well as those living in the islands and poor regions of the country.Key words: Socio-demographic factors: Obesity: Abdominal adiposity: Waist:height ratio: BMI The prevalence of overweight and obesity in the world is growing every year (1) . In Europe, in particular, geographic variation in obesity occurrence was observed, with the rates being higher in central, eastern and southern countries than in northern and western ones (2,3) . On the basis of the European Nutrition and Health Report 2009, overweight and obesity prevalence was the highest in Cypriot men (83 %) and Greek women (73 %) and the lowest in Dutch men (42 %) and Norwegian and Austrian women (31 %) (3) . In Portugal, two representative national surveys conducted in 1995-1998 and 2003-2005 showed that overweight and obesity prevalence in adults increased from 49·6 to 53·6 % (4) . Between 2004 and 2009, the same rates increased from 54 to 60 % in men and from 46 to 49 % in women (3) . The prevalence of obesity in Portuguese adults increased about 20 % (from 12·8 to 15·4 %) between 2000 and 2010 (5) .Because of substantial health consequences, as an important risk factor of non-communicable diseases (NCD) that entails high costs of treatment, the increasing prevalence of overweight and obesity is one of the most important challenges in public health (1,3,5,6) . The World Health Organization (1) reported that in the past 10 years the occurrence of NCD risk factors h...