OBJECTIVE: To estimate the prevalence of symptomatic knee osteoarthritis (OA) in China. METHODS: Using data collected from the China Health and Retirement Longitudinal Study, a population-based longitudinal survey conducted between 2011 and 2012, we estimated the prevalence of symptomatic knee OA according to sex, age, rural/urban area, socioeconomic status, and geographic region. RESULTS: Among 17,128 individuals (8,367 men and 8,761 women; mean age 59.8 years) included in the analysis, 8.1% had symptomatic knee OA. The prevalence of symptomatic knee OA was higher in women (10.3%) compared with men (5.7%) (adjusted odds ratio [OR] 1.88 [95% confidence interval 1.64-2.17]). The prevalence of symptomatic knee OA increased with age (P for trend <0.01). Symptomatic knee OA was more common in rural areas than in urban areas (OR 1.84 [95% confidence interval 1.46-2.31]). The prevalence of symptomatic knee OA was lower among individuals who had received more years of education and who lived in more developed areas (P for trend <0.01). The North and East regions of China had the lowest prevalence of symptomatic knee OA (5.4% and 5.5%, respectively), followed by the North-East (7.0%), South-Central (7.8%), and North-West (10.8%) regions. The prevalence was highest (13.7%) in subjects living in the South-West region. CONCLUSION: Symptomatic knee OA in China was prevalent, and the prevalence varied according to sociodemographic, economic, and geographic factors. Epidemiologic studies identifying risk factors that contribute to variation in the prevalence of symptomatic knee OA in China are warranted.