Cynomolgus monkey CCL11 (C-C motif chemokine ligand 11), also known as eotaxin-1, is a member of the CC chemokine family that regulates eosinophil recruitment and type 2–associated immune responses in Cynomolgus monkeys (Macaca fascicularis). The CCL11 protein is highly conserved among non-human primates and is functionally comparable to that of Rhesus monkey (Macaca mulatta) and humans. CCL11 is produced primarily by epithelial cells, fibroblasts, endothelial cells, and activated immune cells in response to Th2-associated cytokines such as IL-4 and IL-13, and it signals predominantly through the CCR3 receptor to promote chemotaxis and activation of eosinophils, as well as certain Th2 lymphocytes and basophils. In healthy Cynomolgus monkeys, circulating CCL11 levels are typically low, but concentrations may increase during allergic inflammation, parasitic infection, airway hypersensitivity, or experimental immune challenge. In preclinical and translational research, Cynomolgus monkey CCL11 is particularly relevant in models of asthma, allergic disease, parasitology, and evaluation of immunomodulatory biologics targeting Th2 or eosinophil-associated pathways. Characterization of CCL11 in Cynomolgus monkeys provides valuable insight into eosinophilic inflammation, chemokine-driven leukocyte trafficking, and translational mechanisms underlying allergic and type 2–mediated immune responses.