OBJECTIVE: Previous studies have examined the association between breastfeeding and rheumatoid arthritis (RA), but their results were inconsistent. The aim of this study was to perform a metaanalysis to clarify the effect of breastfeeding on RA risk. METHODS: The PubMed, EMBASE, Chinese National Knowledge Infrastructure, and Wanfang databases were searched for relevant studies published up to September 10, 2014. Data were extracted, and multivariable-adjusted OR with 95% CI were pooled in the random-effects model. RESULTS: A total of 6 studies were included in the metaanalysis (RA cases: 1672, sample size: 143,670). Overall, an inverse association between breastfeeding and RA was observed (OR 0.675, 95% CI 0.493-0.924, p = 0.014). In the subgroup analysis, decreased RA risk was also found in both breastfeeding 1-12 months (OR 0.783, 95% CI 0.641-0.957, p = 0.015) and breastfeeding > 12 months (OR 0.579, 95% CI 0.462-0.726, p < 0.0005). Sensitivity analysis and cumulative analysis further strengthened the validity of the results. No publication bias was found in this metaanalysis. CONCLUSION: This metaanalysis suggests that breastfeeding is associated with a lower risk of RA, no matter if breastfeeding time is longer or shorter than 12 months