OBJECTIVE: This article presents information on the origin of leukotrienes (LTs) and the development of antileukotriene (anti-LT) agents. After reading this article, readers should have an understanding of the chemical mediators involved in the pathogenesis of asthma, the structural features of LTs, and the role of anti-LTs in the management of asthma symptoms. DATA SOURCES: Studies considered relevant and appropriately controlled were used. Only literature in the English language was reviewed. STUDY SELECTION: Material was taken from academic/scholarly journals and abstracts. RESULTS: One of the important chemical mediators implicated in the pathogenesis of asthma is the slow-reacting substance of anaphylaxis, which was subsequently found to comprise LTs C4, D4, and E4. 5-lipoxygenase products from arachidonic acid metabolism, LTs are released from the lung tissue of asthmatic patients and purified human lung mast cells by antigens. The LTs directly induce contraction of bronchial smooth muscle. The use of anti-LT agents, particularly the receptor antagonists zafirlukast and montelukast and the biosynthesis inhibitor zileuton, reverses the bronchoconstrictive effects of LTs and significantly improve asthma symptoms. CONCLUSIONS: Extensive in vitro and in vivo evidence supports the role of LTs in the pathogenesis of asthma. Their discovery has had a significant impact on treatment strategies, including the use of anti-LT agents, for the management of asthma.