Osthole, an active coumarin extracted from the dried fruits of Cnidium monnieri (L) Cusson, is known to possess a variety of pharmacological activities. In the present study, we investigated and illuminated the mechanisms underlying the protective effects of osthole in an experimental model of allergic asthma. Our results show that osthole treatment significantly reduced the OVA-induced increase in serum IgE and inflammatory cytokines (IL-4, IL-5, IL-13) in bronchoalveolar lavage fluid (BALF), and decreased the recruitment of inflammatory cells in BALF and the lung. It also effectively attenuated goblet cell hyperplasia and mucus overproduction in lung tissue. In addition, western blot analysis demonstrated that osthole blocked NF-kappa B activation, which may be associated with a reduction in inflammatory cytokine production. These data suggest that osthole attenuated OVA-induced allergic asthma inflammation by inhibiting NF-kappa B activation. The present study identified the molecular mechanisms of action of osthole, which support the potential pharmaceutical application of osthole treatment for asthma and other airway inflammation disorders. (C) 2017 Published by Elsevier B.V.