OBJECTIVES: Osteoarthritis is the most common joint disease, with a higher prevalence among women than men. The present study aimed to examine the associations of breastfeeding duration and the total number of children breastfed with osteoarthritis in Korean women aged 50 years and older. METHODS: In this cross-sectional study, we used representative data from the Korea National Health and Nutrition Examination Survey, phases 5 through 7 (2010-2018). Our analysis included 10,102 women aged ≥50 years. Osteoarthritis experience was defined as whether a physician had ever diagnosed osteoarthritis. Breastfeeding duration was categorized as 1-6 months, 7-24 months, and ≥25 months. The total number of children breastfed was categorized as 1-2, 3-4, and ≥5. The covariates were health behavior characteristics and risks of diseases (smoking, drinking, physical activity, body mass index, diabetes, hypertension, oral contraceptive use, and menopause) as well as socioeconomic characteristics (income, educational level, and occupation). A multiple logistic regression model was used to investigate associations between osteoarthritis and aspects of breastfeeding experience. RESULTS: Compared to the non-breastfeeding group, the breastfeeding group had an odds ratio (OR) of 1.55 (95% confidence interval [CI], 1.18 to 2.03) for osteoarthritis. Those who reported breastfeeding for >25 months had an OR of 1.56 (95% CI, 1.19 to 2.06). CONCLUSIONS The advantages of breastfeeding are already well known, but the present study suggests that women who breastfeed children for a longer time may have a higher risk of osteoarthritis after middle age.