The development of Ewing's sarcoma (ES) is a complex process resulting from interplay between mutations in oncogenes and tumor suppressors, host susceptibility factors, and cellular context. CD86 (B7-2) may affect cancer susceptibility by modulating T cell response. CD86 +1057G/A polymorphism (rs1129055) has been reported to be associated with various diseases. Here, we investigated the association between CD86 +1057G/A polymorphism and the risk of ES in a Chinese population. The CD86 +1057G/A polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism in 158 ES cases and 212 age-matched healthy controls. Frequencies of CD86 +1057 AA genotype and +1057 A allele were significantly increased in patients with ES compared to healthy controls (odds ratio [OR]=2.12, 95% confidence interval [CI], 1.11-3.79, p=0.021; and OR=1.41, 95% CI, 1.10-1.91, p=0.018). Our data suggest that the +1057G/A polymorphism of the CD86 gene is associated with increased susceptibility to ES.