The immunoreactivity of six different monoclonal antigranulocyte antibodies (Leu M1, TG1, 3C4, BY/87a, BY/37a, and 3CD1) has been evaluated in 23 cases of Hodgkin's disease (7 lymphocyte predominant, 12 nodular sclerosing, and 5 mixed cellularity); in a variety of non-Hodgkin's lymphomas and in a series of reactive and benign lesions of lymph nodes. Applying a monoclonal antibody (PD7/26) to leukocyte common antigen (T200), we have also investigated reports that the L&H variants in nodular lymphocyte predominant Hodgkin's disease are strongly immunoreactive for leukocyte common antigen in contrast to the lack of reactivity of Reed-Sternberg (RS) cells and variants thereof in other forms of Hodgkin's disease. All six monoclonal anti-granulocyte antibodies reacted against RS cells and "Hodgkin's cells" in the nodular sclerosing (NSHD) and mixed cellularity (MCHD) types, with strong cell membrane and juxtanuclear (Golgi) staining. In contrast an anti-leukocyte antibody PD7/26 was unreactive with RS cells and variants thereof in NSHD and MCHD. On the other hand, RS cells and L&H variants thereof in the nodular L&H form of Hodgkin's disease (nodular lymphocyte predominant type) showed reactivity with PD7/26 but not with the anti-granulocyte markers. Rare L&H cells in 2 cases of diffuse lymphocyte predominant type showed reactivity with some, but not all, of the anti-granulocyte antibodies. These findings provide further support for the concept that the nodular L&H type of Hodgkin's disease represents an entity distinct from other forms of this disorder. Our studies also demonstrate the usefulness of these immunoperoxidase techniques when applied to formalinfixed, paraffin-embedded tissues.