Objective: To investigate the prevalence of osteoarthritis (OA) in a population aged >= 50 years in Ireland, and to determine its relationship with demographic and health-related variables. Methods: Cross-sectional data from Wave 1 of The Irish Longitudinal Study on Ageing (TILDA), a population-based study of 8175 people aged >= 50 years were analyzed. Logistic regression was used to determine associations between the presence of OA and a range of demographic and health-related variables. Results: A total of 8175 people >= 50 years in Ireland were identified from the TILDA database of whom 45.7% (n = 2941) were male and 54.3% (n = 4431) were female. The overall prevalence of OA was 12.9% (women-17.3%; men-9.4%). Prevalence increased with age, with prevalence in those aged >= 80 years twice that [17.7%; 95% confidence interval (CI) 13.97, 21.54] of those aged 50-60 years (8.23, 95% CI 7.32, 9.13). On multivariable analysis, OA was significantly associated (P < 0.02) with female gender, older age, pain severity, higher body mass index (BMI), fear of falling, greater number of physical limitations and medication use. In particular, there was a strong association between the use of NSAIDS and the presence of OA [adj odd ratio (OR) = 5.88, 95% CI 4.16, 8.31]. A significant association was also found between OA and increasing number of chronic diseases (adj OR= 2.75 9, 95% CI = 2.44, 3.09). Conclusions: OA is a common and multifaceted condition, with comparable prevalence of self-reported OA in Ireland with similar populations. Assessment and management should focus on potentially modifiable factors such as BMI, pain, physical limitations, polypharmacy and fear of falling. More research is required to understand the complex inter-relationships between these and other risk-associated variables.