Abstract This study examines the contribution of the lipoxygenase products of arachidonic acid, termed hydroxy-eicosatetraenoic acids or HETEs, to the neutrophil chemotactic activity elaborated by rabbit alveolar macrophages. The predominant neutrophil chemotactic activity released by phagocytosing alveolar macrophages exhibits a molecular weight of 300–800, as assessed by Sephadex G25 filtration, and cochromatographs with defined HETE standards on silica gel H thin-layer plates. The chemotactic factors generated by the alveolar macrophages were identified by gas chromatography and mass spectroscopy as 5-HETE and 11-HETE. The quantities of 5-HETE and 11-HETE released from alveolar macrophages at 1 and 4 hr were increased up to five-fold by phagocytosis. Incubation of the alveolar macrophages with the lipoxygenase inhibitor 5,8,11,14-eicosatetraynoic acid prior to phagocytosis eliminated completely the stimulation of the generation of both the HETEs and the neutrophil chemotactic activity. The neutrophil chemotactic activity produced by phagocytosing alveolar macrophages thus is attributable largely to 5-HETE and 11-HETE.