This study was performed to examine whether the AF4/FMR2 family, member 1 (AFF1) rs340630 polymorphism is involved in the genetic background of rheumatoid arthritis (RA) in a Chinese population. Two different study groups of RA patients and controls (328 RA patients and 449 healthy controls in the first study group; 232 RA patients and 313 controls in the second study group) were included in our study. Overall, there was no significant difference in either genotype (P=0.71 and 0.64 in the first and second study group, respectively) nor allele (in the first study group: A vs G, P=0.65, OR=1.05, 95%CI=0.85–1.29; in the second study group: G vs A, P=0.47, OR=1.10, 95%CI=0.86–1.40) frequencies of AFF1 rs340630 polymorphism between RA patients and controls. Our study represents the first report assessing the association of AFF1 rs340630 polymorphism with RA risk. No significant evidence was found for the dominant or recessive models. Further case-control studies with larger sample sizes and fine-mapping studies are needed to clarify the role of AFF1 in the genetic basis of RA.