Aim: To determine the prevalence of osteoporosis in both women and men and to determine the association between osteoporosis and selected risk factors among a sample of urban Sri Lankan adults. Methods: The population aged 35-64 years residing in 22 Grama Niladhari divisions, the smallest administrative units in the country, of the Medical Officer of Health area Ragama, Sri Lanka, was identified using the electoral list and stratified into three age groups (n = 3012). A random sample was obtained from each stratum and selected individuals were invited to participate in the study (n = 1100). A structured, interviewer-administered questionnaire was used to collect information on demographic data and details of risk factors. Bone mineral density (BMD) was measured using a peripheral dual-energy X-ray absorptiometry (DEXA) scan in 700 subjects (64%). A BMD < -2.5 was considered as osteoporosis. Although peripheral DEXA is less sensitive and specific compared to central DEXA it was used in this study as it is less costly and easily transportable. Results: Of the 700 subjects who consented to participate in the study, 60% (n = 421) were females. In subjects < 50 years, 9% of women and 3% of men had osteoporosis. In subjects ≥ 50 years, 27% of women and 7% of men had osteoporosis. Female sex (odds ratio [OR] 12.0), smoking (OR 5.5), age > 50 years (OR 3.1), low BMI (OR 3.1) and low level of education (OR 1.7) were positively associated with osteoporosis. Conclusions: Female sex, age, BMI, smoking and level of education were significant predictors of osteoporosis. The prevalence of osteoporosis increased in both women and men after 50 years. © 2010 The Authors. International Journal of Rheumatic Diseases. © 2010 Asia Pacific League of Associations for Rheumatology and Blackwell Publishing Asia Pty Ltd.