There are few data on the reactivity of Reed-Sternberg (RS) cells with antibodies against vimentin. In a preliminary survey of biopsy specimens from 16 cases of Hodgkin's disease (HD), we found that the antivimentin (V9) monoclonal antibody stained RS cells in 6 cases. We therefore examined vimentin expression on RS cells immunohistologically in 38 Bouin-fixed and paraffin-embedded lymph nodes with HD [lymphocyte predominance (LP) 4; nodular sclerosis (NS) 23; mixed cellularity (MC) 7; lymphocyte depletion (LD) 4]. The results were correlated with the histopathological features, the immunohistological phenotype of the RS cells, and the findings obtained from molecular genetics studies (available in 13 cases). RS cells were found to express strong and diffuse cytoplasmic staining for vimentin in 13 cases, all of the NS subtype. No differences in antigenic expression on RS cells were found between the vimentin-positive and negative cases within the NS subtype. DNA analysis revealed no B- or T-cell clonal populations in the tested samples. The results indicated that RS cells were immunostained by anti-vimentin (V9) antibody with a relatively high frequency, but only in the NS subtype of HD. This subtype, however, was heterogeneous according to vimentin immunostaining on RS cells. The significance of this finding concerning the RS cell origin in this subset is discussed.