The purpose of this study was to estimate the prevalence of radiographic and symptomatic knee osteoarthritis (OA) among community residents and to elucidate the relevant risk factors. This prospective, population-based study was conducted on residents over 50 yr of age in Chuncheon. Subjects completed an interview based on a standardized questionnaire and clinical evaluation including standardized weight bearing semiflexed knee A-P radiographs. We defined a subject with the Kellgren and Lawrence grade ≥2 as having radiographic knee OA (ROA). Symptomatic knee OA (SOA) was defined by the presence of both ROA and knee pain. We obtained symptom information and radiographs from 504 subjects. The prevalence of ROA and SOA was 37.3% and 24.2%, respectively. The prevalence of both ROA and SOA was significantly higher among women than among men. Multivariate analysis revealed that the presence of hypertension, and a manual occupation were significantly associated with the presence of ROA and SOA. Lower level of education was significantly associated with the presence of ROA, and female sex with the presence of SOA. In conclusion, both ROA and SOA are common in the aged adult population of Korea, with preponderance for women.