Cynomolgus monkey CCL19 (C-C motif chemokine ligand 19), also known as macrophage inflammatory protein-3β (MIP-3β) or EBI1 ligand chemokine (ELC), is a member of the CC chemokine family that plays a central role in lymphocyte trafficking and organization of secondary lymphoid tissues in Cynomolgus monkeys (Macaca fascicularis). The CCL19 protein is highly conserved among non-human primates and is functionally comparable to that of Rhesus monkey (Macaca mulatta) and humans. CCL19 is produced primarily by stromal cells, dendritic cells, and macrophages within lymph nodes, spleen, and other lymphoid organs, where it signals through the CCR7 receptor to direct migration of naïve and central memory T cells, regulatory T cells, and mature dendritic cells. This CCR7–CCL19 axis is essential for antigen presentation, T cell priming, and maintenance of lymphoid architecture. In healthy Cynomolgus monkeys, CCL19 supports immune surveillance and adaptive immune organization; expression may increase during infection, vaccination, inflammatory stimulation, or immune-modulating biologic treatment. In preclinical and translational research, Cynomolgus monkey CCL19 is particularly relevant in studies of vaccine immunogenicity, autoimmune disease models, transplant immunology, and evaluation of immunotherapeutics, providing insight into CCR7-mediated immune cell trafficking and adaptive immune regulation in non-human primate models.