Chicken Leukemia Inhibitory Factor (LIF) is a multifunctional cytokine belonging to the IL-6 family—which in mammals includes IL-6, IL-11, oncostatin M (OSM), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine factor 1 (CLCF1), and IL-27—all of which signal through receptor complexes containing the shared gp130 subunit. In chickens (Gallus gallus), LIF binds to the LIF receptor (LIFR) in association with gp130, activating JAK/STAT3, MAPK, and PI3K signaling pathways that regulate cell survival, differentiation, and immune modulation. Avian LIF plays important roles in embryonic development, hematopoiesis, and maintenance of pluripotency in early embryonic cells, and has been studied in the context of avian stem cell biology and primordial germ cell culture. In poultry health, LIF may contribute to regulation of inflammatory responses during infections such as avian influenza virus, Newcastle disease virus, and bacterial challenges, where STAT3-mediated signaling influences tissue repair and immune balance. Dysregulated LIF expression could impact fibrosis, tumor development (e.g., Marek’s disease), or chronic inflammation. As both a developmental and immunomodulatory cytokine, chicken LIF is relevant in studies of embryo culture systems, vaccine responses, oncogenic viral disease, and cytokine network regulation. Characterization of chicken LIF supports research into avian developmental biology, immune regulation, and comparative IL-6 family signaling across vertebrate species.