Agents that modulate the effects of eicosanoids have proved to be important therapeutics. In the early 1990s a number of agents that modulate the actions or synthesis of leukotrienes were optimized and tested in asthma. This major effort provided for the approval of two CYSLT1 antagonists, montelukast and zafirlukast; and one 5‐lipoxygenase inhibitor, zileuton, which proved effective in the treatment of asthma. More recently, the breakthrough discovery of a second cyclooxygenase isozyme, COX‐2, provided the impetus for the discovery of selective COX‐2 agents. These agents, which include celecoxib, rofecoxib, and valdecoxib, have been shown to have significant anti‐inflammatory and analgesic effects while being gastric sparing, in contrast to nonselective cyclooxygenase inhibitors commonly referred to as NSAIDs. The gastric‐sparing properties of these agents and others currently in development should open new therapeutic modalities. One of the most exciting of these is in the prevention and treatment of cancer.