It is now established that 5-lipoxygenase products are synthesized and released in the airway during asthmatic reactions. The importance of these products in the asthmatic response has been established through study of the effects of 5-lipoxygenase inhibitors and leukotriene D4 receptor antagonists in patients with chronic stable asthma. In this study we review the data demonstrating that chronic administration of zileuton, an inhibitor of 5-lipoxygenase, is associated with improved airway function, decreased asthma symptoms and decreased need for asthma medication use in patients with mild to moderate asthma.