The aim of the present study was to assess the prevalence, extent, and risk indicators of tooth loss in a representative adult, urban population in the Brazilian state of Rio Grande do Sul. A sample of 974 subjects (ages 30 to 103 years, mean 48.7, SD 13.4) representative of the metropolitan area of Porto Alegre, Brazil was selected by a multi-stage probability cluster sampling strategy. In all, 94% of the subjects had experienced tooth loss. The mean tooth loss was 11.2 teeth, and varied between 5.5 and 20.2 teeth in the 30-39 and 60 + years age groups, respectively. The multivariable analysis, adjusted for age, showed that subjects who had lost 7-13 or > or = 14 teeth were more likely to be females (odds ratio (OR) = 1.4, 2.4), of low (OR = 2.8, 5.1) or middle socio-economic status (OR = 2.3, 3.4), and heavy smokers (OR= 2.0, 2.3) than those with 6 or fewer missing teeth. Furthermore, loss of > or = 14 teeth was associated with presence of > 50% teeth with attachment loss > or = 5 mm (OR= 5.7), and loss of 7-13 teeth was associated with presence of > 50% teeth with attachment loss > or = 5 mm (OR = 2.4) and having 15-30% or > 30% decayed-filled teeth (OR = 2.7 and 4.1). In conclusion, tooth loss is highly prevalent in this urban Brazilian population. Gender, socio-economic status, cigarette smoking, caries experience, and attachment loss are important risk indicators. A reduction in the population's tooth loss may be achieved by the implementation of community programs for the prevention and treatment of dental caries and periodontal diseases.