Lipid products derived from the metabolism of arachidonic acid have a central role in inflammatory reactions and probably contribute to the pathophysiology of bronchial asthma as well as other obstructive diseases of the lung. Metabolites of arachidonic acid also modulate numerous physiologic responses. The goal of pharmacologic intervention is to enhance the beneficial effects of certain arachidonate metabolites and to inhibit those which are undesirable. Development of new pharmacologic agents which selectively inhibit synthesis or action of certain arachidonic acid metabolites, particularly the bronchospastic leukotrienes, may provide more effective treatment of asthma in the future.