Chicken CCL4 (C-C motif chemokine ligand 4, also known as MIP-1β, macrophage inflammatory protein-1 beta–like chemokine in birds) is a pro-inflammatory chemokine involved in recruitment and activation of immune cells during inflammatory and infectious responses in chickens (Gallus gallus). CCL4 functions through chemokine receptors homologous to mammalian CCR5, promoting chemotaxis of monocytes, macrophages, dendritic cells, natural killer–like cells, and activated T lymphocytes to sites of infection or tissue injury. In chickens, CCL4 is produced by activated macrophages, epithelial cells, and lymphocytes in response to inflammatory stimuli such as pathogen-associated molecular patterns and cytokines including IL-1β and TNF-like mediators. CCL4-mediated immune cell recruitment plays an important role in host defense against pathogens responsible for avian influenza, Newcastle disease, infectious bronchitis, and bacterial infections such as Salmonella and Mycoplasma gallisepticum. By directing leukocyte trafficking to infected tissues, CCL4 helps coordinate innate and adaptive immune responses and contributes to pathogen clearance. However, excessive or prolonged expression may contribute to inflammatory tissue damage. As a regulator of leukocyte migration and inflammatory signaling, chicken CCL4 is important for studies of avian host–pathogen interactions, immune regulation, and vaccine responses, supporting research aimed at improving disease resistance and flock health in poultry production systems.