CXCR5, also known as Burkitt Lymphoma Receptor 1, is a G protein-coupled receptor (GPCR) member of the CXC subfamily of chemokine receptors. Human CXCR5 is 372 amino acids (aa) in length with a predicted molecular weight of 42 kDa. Mouse and rat CXCR5 share 83% and 81% aa sequence identity with the human protein, respectively. CXCR5 is primarily expressed on B cells and binds CXCL13/BCL/BCA-1. The CXCL13/BCL/BCA-1:CXCR5 axis regulates B cell migration within secondary lymphoid organs such as the spleen and Peyer’s patches. CXCR5 is also expressed on follicular helper T cells and dermal-derived migratory dendritic cells where it is thought to promote the humeral immune response by meditating germinal center reactions and B cell activation. Polymorphisms of CXCR5 are associated with multiple types of non-Hodgkin’s lymphoma, and it is expressed on Burkitt’s lymphoma cells.