Abstract: AimTo study the effect of montelukast on apoptosis and Fas mRNA expression of eosinophils in airway of asthmatic guinea pigs. MethodsExperimental asthma model of guinea pigs was induced by ovalbumin. The eosinophils in broncho-alveolar lavage fluid (BALF) were separated by density gradient centrifugation. The apoptosis of eosinophils was labeled by TdT-mediated dUTP nick end labeling (TUNEL) technique. Fas mRNA expression of eosinophils was detected by reverse transcription-polymerase chain reaction (RT-PCR). ResultsAfter treatment with montelukast, the number of eosinophils in BALF of asthmatic guinea pigs decreased significantly. The apoptosis index as well as Fas mRNA expression of eosinophils were elevated significantly. There were statistical differences between the therapeutic group and the model group. ConclusionApoptosis of eosinophils is highly correlated with the increased expression of Fas mRNA. Enhancing expression of Fas mRNA and promoting apoptosis of eosinophils subsequentely may be an important mechanism for montelukast to antagonize airway inflammation of asthma.