Leukotrienes are biological active lipids produced from arachidonic acid in cell membrane by the enzyme 5-lipoxygenase. During anaphylaxis, large amounts of leukotrienes are generated in the lungs, causing bronchoconstriction. Leukotrienes exacerbate asthma in different ways including cellular infiltration, chemotaxis aggregation, and degranulation (LTB4), as well as airway constriction, vasopermeability, mucous hypersecretion, mucosal edema and reduced mucociliary clearance (LTC4, LTD4 and LTE4). It is expected that 5-lipoxygenase inhibitors are effective in bronchial asthma by blocking leukotriene synthesis, and its indication is chronic therapy to prevent symptoms of bronchospasm. Zileuton is the 5-lipoxygenase inhibitor most advanced in clinical development. As bronchial asthma is thought to be provoked by a variety of causes, therapeutic drug should be selected according to the state of the disease.