Chicken Interleukin-13 (IL-13) is a Th2-associated cytokine produced primarily by CD4⁺ T helper–like cells and other type 2 immune populations in chickens (Gallus gallus), where it plays an important role in regulating mucosal immunity, alternative macrophage activation, and modulation of inflammatory responses. IL-13 signals through receptor components homologous to IL-4Rα and IL-13Rα chains, activating JAK/STAT6-dependent pathways that influence gene expression involved in mucus production, antibody-associated responses, and suppression of excessive pro-inflammatory cytokine signaling. In poultry health, IL-13 is particularly relevant in immune responses to parasitic infections such as Eimeria spp. (coccidiosis) and helminths, where Th2 polarization contributes to parasite control and intestinal tissue repair. IL-13 may also influence immune regulation during viral infections such as avian influenza virus and Newcastle disease virus by shaping the balance between Th1 and Th2 responses. Dysregulated IL-13 expression can contribute to chronic inflammation, impaired pathogen clearance, or altered growth performance. As a biomarker of type 2 immune activation, chicken IL-13 is important in studies of vaccine development, host–parasite interactions, and genetic selection for disease resistance. Characterization of chicken IL-13 supports comparative immunology research into Th2-mediated immunity and cytokine network regulation in avian species.