Abstract: AimTo investigate the effect of inhalation of cyclosporin (CsA) on antigen-induced airway inflammation in Sprague-Dawley rats. MethodsRats were sensitized with antigen (ovalbumin, OA). After two weeks, the sensitized rats were pretreated with aerosol CsA (5, 10, 20 g·L^-1)，once per day for 7 days. Then, the sensitized rats were challenged with OA (10 g·L^-1，once per day) for 2 days at day 20 after sensitization. The number of eosinophils in bronchoalveolar lavage fluid (BALF) and peripheral blood, histological changes of lung tissue, and TNF-α content in BALF were investigated. ResultsInhalation of CsA significantly reduced the number of eosinophils in BALF and peripheral blood, inflammatory infiltration and tissue edema of lung tissue, decreased the content of TNF-α in BALF. ConclusionInhalation of CsA inhibited airway inflammation in rats, and the mechanism is related to inhibition of TNF-α release.