Many monoclonal antibodies reactive with bovine leukocyte differentiation antigens are now available. Immunohistochemical staining on frozen sections using these monoclonal antibodies permits study of the functional morphology of bovine lymph nodes. Our study confirms usually accepted notions (B and T dependent-zones) and supplies complementary data about the repartition of CD4 cells (particularly intrafollicular positive cells), gamma delta T cells, MHC II expression and dendritic leukocytes.