Objective : Osteoarthritis is one of the most common joint disorder in the world. But unfortunately there is no fundamental data as to its prevalence and risk factors in Korean population. We performed this study to understand the prevalence and risk factors related to knee osteoarthritis in Koreans. Material and Methods : A total 867 persons aged 20-69 years were selected from the general population in Kuri city and underwent a structured interview, clinical examination of knee joint, and radiologic study. The diagnostic criteria of knee osteoarthritis which we used was composed of clinical and radio- logical criteria reported by Altman et al. General characteristics of prevalence of knee osteoarthritis in relation to age, sex, education, job were evaluated. Risk factors such as obesity, menopause, physical activity, smoking, drinking, osteoporosis, diabetes mellitus, hypertension were evaluated by chi-squre test and logistic regression. Results : This study revealed that prevalence of knee osteoarthritis in Korea is 10.2%, increasing with age. High level of physical activity in men and age, postmenopause and obesity in women can be risk factors.