Objective:The present study was to investigate the antiasthmatic potential from the flavonoid fraction of Apium leptophyllum fruit (FFALF) to validate its traditional claim.Materials and Methods:The antiasthmatic activity of FFALF was evaluated by histamine or acetylcholine-induced bronchospasm model in guinea pigs, compound 48/80 induced mast cell degranulation in albino rats and histamine-induced tracheal contraction in guinea pig. The preconvulsion dyspnea time at 0th and 7th day at the dose of 100 and 200 mg/kg in guinea pig's bronchospasm model, the percentage of granulated and degranulated mast cell at the dose of 500, 750, and 1000 μg/ml in rats and tracheal contraction at the dose of 500, 750, and 1000 μg/ml in guinea pig were measured and compared with respective control groups.Results:The treatments of FFALF were significantly (P < 0.001) decreased the histamine/acetylcholine-induced bronchospasm, mast cell degranulation, and histamine-induced tracheal contraction as compared to inducer group. In addition, FFALF showed dose-dependent antiasthmatic activity in all the animals.Conclusion:Hence, this study suggested that the FFALF showed antiasthmatic activity probably by membrane stabilizing property as well as suppressing antibody production and inhibiting of antigen induced by histamine and acetylcholine.