Arachidonic acid metabolites are potent modulators in physiology and mediators in pathophysiology of airways. They play important role in allergic diseases. There are two main sources of eicosanoids found in nasal and bronchial lavages: airway epithelial cells and influx cells. Authors described spectra of eicosanoids produced by epithelial cells in vitro and compare them with in vivo findings. The review of similarities and differences between arachidonic acid metabolism in human upper and lower airways is also included.