Immunohistological studies of the murine liver following Leishmania donovani infection have been performed. We describe here the identification of cells expressing a recently defined dendritic cell marker, as detected by monoclonal antibody NLDC 145. Such cells are numerous in the developing inflammatory foci but are not detected individually at any other site in the infected liver. This finding suggests that mature tissue DC are not recruited during infection and that expression of this antigen is under precise microenvironmental control.