Background: Chemokines play important roles in inflammation and antiviral action. We examined whether polymorphisms of RANTES, IP-10 and Mig affect the susceptibility to and outcome of severe acute respiratory syndrome (SARS). Methods: We tested the polymorphisms of RANTES, IP-10 and Mig for their associations with SARS in 495 Hong Kong Chinese SARS patients and 578 controls. Then we tried to confirm the results in 356 Beijing Chinese SARS patients and 367 controls. Results: RANTES -28 G allele was associated with SARS susceptibility in Hong Kong Chinese (P < 0.0001, OR = 2.80, 95%CI:2.11-3.71). Individuals with RANTES -28 CG and GG genotypes had a 3.28-fold (95%CI:2.32-4.64) and 3.06-fold (95%CI:1.47-6.39) increased risk of developing SARS respectively (P < 0.0001). This -28 G allele conferred risk of death in a gene-dosage dependent manner (P = 0.014) with CG and GG individuals having a 2.12-fold (95% CI: 1.11-4.06) and 4.01-fold (95% CI: 1.30-12.4) increased risk. For the replication of RANTES data in Beijing Chinese, the -28 G allele was not associated with susceptibility to SARS. However, -28 CG (OR = 4.27, 95%CI:1.64-11.1) and GG (OR = 3.34, 95%CI:0.37-30.7) were associated with admission to intensive care units or death due to SARS (P = 0.011). Conclusion: RANTES -28 G allele plays a role in the pathogenesis of SARS.