To assess whether the histological pattern of Hodgkin's disease (HD) in human immunodeficiency virus (HIV)-infected patients differs from that among HD patients without HIV infection, the observed (O) number of HD cases according to histological subtype [i.e. lymphocyte predominance (LP), nodular sclerosis (NS), mixed cellularity (MC) and lymphocyte depletion (LD)] among 92 Italian HIV-infected patients was compared with the expected (E) number derived from two case series of HD from Europe and the U.S.A. (14,315 cases of HD) and Italy (125 cases). After age standardisation, the O/E ratio was computed, along with its 95% confidence interval (CI). In comparison with 125 Italian HD patients not infected with HIV, a 4-fold higher frequency of the MC histological subtype (95% CI: 2.9-5.1) and an approximately 12-fold higher frequency of the LD subtype (95% CI: 7.0-18.0) emerged among HIV-infected patients. These results were substantially confirmed when the comparison was made with the case series from Europe and the U.S.A. These data show different histological patterns of HD between a group of HIV-infected patients and HD patients from the general population. Although caution is needed in their interpretation, the study results seem to indicate that HD of the MC or LD subtypes may be considered an AIDS-related malignancy.