Abstract: Objective　To study the regulatory role of chemerin in infant with respiratory syncytial virus (RSV) pneumonia by investigating the level of serum chemerin，pro-inflammatory cytokine (TNF-α, IL-17), and anti-inflammatory cytokine (IL-10, TGF-β). Methods　The serum level of chemerin，TNF-α，IL-1，IL-10，TGF-β were tested in 82 RSV pneumonia inpatients (17 severe RSV pneumonia cases，65 mild cases) and 40 controls by ELISA and the severity of the RSV pneumonia was evaluated using a scoring system. Results　The serum level of chemerin of RSV pneumonia cases were (610.45±106.63pg/ml) which were significantly higher than the control(337.24±43.37 pg/ml). Chemerin level of severe RSV pneumonia group is significantly higher than mi d cases as well [(786.62±82.59 pg/ml)vs (539.98±65.86 pg/ml)P ＜ 0.01 ]. Significant positive correlations were found between serum chemerin level and TNF-α，IL-17 level (r=0.81，r=0.61；P ＜ 0.01) while the serum level of chemerin is negatively correlated with IL-10, TGF-β (r=-0.80，r=-0.75；P ＜ 0.01). Conclusions　The level of chemerin increased in RSV pneumonia patients，and related to clinical severity after RSV infection. These results indicate that chemerin may play an important role in the pathogenesis of RSV pneumonia and to the severity of the infection.