Objective To investigate the effects of montelukast ( MK) on the airway inflammation and the risk of the recurrence of wheezing in the treatment of infants with RSV bronchiolitis.Methods 60 infants ( aged 6-24 months) with RSV bronchiolitis admitted between December 2010 and December 2011 were recruited in the study. They were randomly assigned into a conventional group and a MK group ( n =30 in each group) . All patients received conventional treatments including inhalation of budsonide and so on.The subjects in the MK group received oral montelukast ( 4 mg qn for 12 weeks) additionally. The levels of serum cysteinyl leukotrienes ( CysLTs ) , total immunoglobuline E ( T-IgE) , eosinophil cationic protein ( ECP) and fractional exhaled nitric oxide ( FeNO) were assayed before and after the treatments. Thenumber of recurrence of wheezing was recorded through outpatient and telephone follow-up for 12 months. 30 healthy infants participating the health examination in outpatient were selected as control, and those who got atopic disease or respiratory tract infections recently were excluded. Results The levels of CysLTs, ECP and FeNO of the patients with RSV bronchiolitis before treatment were significantly higher than those in the normal control group, and the levels of CysLTs and FeNO were significantly decreased after treatment ( P lt;0. 05) . The levels of CysLTs and FeNO after treatment in the MK group was significantly lower than those in the conventional group. The level of ECP was significantly decreased after treatment in the MK group ( P lt;0. 05) ,·186· Chin J Respir Crit Care Med, March 2013 , Vol. 12 , No. 2 http: / /www. cjrccm. com which was not significantly changed in the conventional group( P gt; 0. 05) . The number of recurrence of wheezing in the MK group was more less that that in the conventional group ( P lt; 0. 05) . Conclusion Maintenance treatment with montelukast after the treatment of the acute phase of bronchiolitis can prevent recurrence of wheezing by suppressing airway inflammation in infants with RSV bronchiolitis.