We describe four cases of Hodgkin's disease that presented histologically as purely follicular lesions. The Reed-Sternberg (RS) cells were of classic and lacunar type and had the phenotype of usual Hodgkin's disease (CD30 and CD15 positive) but also expressed B-cell antigens (CD20 and CD79a). In each case the follicles consisted principally of mantle-zone B cells, which enclosed the RS cells; the follicle centres were atrophic, usually eccentrically placed, and did not contain RS cells. Fifteen cases of typical nodular sclerosing Hodgkin's disease were reviewed in parallel. B-cell antigen expression by RS cells was found in 10 cases (66%), and RS cells were present in follicular mantles in 10 cases. These findings suggest that some RS cells may be derived from B cells in the follicular mantle.