Moringaceae, which belongs to the Moringa oleifera Lam. family, is a well-known herb used in Asian medicine as an antiallergic drug. In the present study, the efficacy of the n-butanol extract of the seeds of the plant (MONB) is examined against ovalbumin-induced airway inflammation in guinea pigs. The test drugs (MONB or dexamethasone) are administered orally prior to challenge with aerosolized 0.5% ovalbumin. During the experimental period, bronchoconstriction tests are performed, and lung function parameters are measured. The blood and bronchoalveolar lavage fluid are collected to assess cellular content, and serum is used for cytokine (tumor necrosis factor-alpha, interleukin-4, and interleukin-6) assays. Histamine assays of lung tissue are performed using lung tissue homogenate. The results suggest that in ovalbumin-sensitized model control animals, tidal volume is decreased, respiration rate is increased, and both the total and differential cell counts in blood and bronchoalveolar lavage fluid are increased significantly compared with nonsensitized controls. MONB treatment shows improvement in all parameters except bronchoalveolar lavage tumor necrosis factor-alpha and interleukin-4. Moreover, MONB treatment demonstrates protection against acetylcholine-induced bronchoconstriction and airway inflammation. These results indicate that MONB has an inhibitory effect on airway inflammation. Thus, MONB possesses an antiasthmatic property through modulation of the relationship between Th1/Th2 cytokine imbalances.