The objectives of this study were to: (1) describe obesity prevalence in a Brazilian city; (2) test the association between obesity and socio-demographic variables; and (3) compare results with a survey in the same city in 1994. A cross-sectional population-based study was carried out in a random sample of 1,968 20-69-year-olds residing in the urban area of Pelotas, Rio Grande do Sul State. Obesity was defined as Body Mass Index (BMI) > 30 kg/m(2). Age and sex-adjusted obesity prevalence was 19.4%. Schooling was not associated with obesity in men. Obesity prevalence was higher in middle-income men. Women with more schooling had lower obesity rates. There was a non-statistically significant reduction in obesity rates compared to a similar study from 1994.