Technical Abstract: Lipoxygenases (LOX) catalyze hydroperoxidation of polyunsaturated fatty acids to form structurally and functionally diverse oxylipins. Precise physiological and biochemical functions of individual members of plant multigene LOX families are largely unknown. Herein we report on detailed molecular and biochemical characterization of two closely related maize 9-lipoxygenase paralogs, ZmLOX4 and ZmLOX5. Recombinant ZmLOX5 protein displayed clear 9-LOX regio-specificity at both neutral and slightly alkaline pH. The genes were differently expressed in various maize organs and tissues as well as in response to different stress treatments. The transcripts of ZmLOX4 accumulated predominantly in roots and shoot apical meristem, whereas ZmLOX5 was expressed in most tested aboveground organs. Although both genes were not expressed in untreated leaves, they displayed differential induction by defense-related hormones. While ZmLOX4 was only induced by jasmonic acid (JA), the transcripts of ZmLOX5 were increased in response to JA, abscisic acid (ABA) and salicylic acid (SA) treatments. ZmLOX5 was transiently induced in response to mechanical wounding and fall armyworm herbivory, suggesting a putative role for this gene in defenses against insects. Surprisingly, despite of JA- and wound-inducibility of ZmLOX4, the gene was not responsive to insect herbivory. These results suggest that the two genes may have distinct roles in maize adaptation to diverse biotic- and abiotic stress. Both paralogs were similarly induced by virulent and avirulent strains of the fungal leaf pathogen Cochliobolus carbonum. Putative physiological roles for the two genes are discussed in the context of their biochemical and molecular properties.