Malignant lymphomas occurring in patients with AIDS are usually derived from the B-cell lineage while T-cell malignant lymphomas are very rare in these patients. We report a HIV seropositive 29-year-old homosexual man in whom cervical lymph node biopsy showed an atypical lymphoproliferative process. On morphological and paraffin section immunohistochemical grounds the possibility of Hodgkin's disease (HD) mixed cellularity was initially suggested, but frozen section immunohistochemical studies revealed that the cellular infiltrate exhibited an aberrant pan T immunophenotype and consequently the diagnosis of peripheral T-malignant lymphomas (T-ML) was made. However, genotypic studies would be required to definitely confirm this diagnosis, in such cases. In our case, varying numbers of small and medium-sized cells were positive for both Leu 3/CD4 and Leu 2/CD8 whereas some large cells reacted only with Leu 3/CD4 antibody. Some medium-sized, large and giant cells showed cytoplasmic positivity for Leu M1/CD15. Furthermore, the positivity of many large and giant cells with the activation markers BerH2/CD30, Ki-1/CD30, Tac/CD25 and HLA-DR suggested an activation state for these cells. Our findings emphasize the usefulness of frozen section immunohistochemical methods in order to investigate the spectrum of lymphoid malignancies occurring in HIV seropositive patients, and confirm results of previous studies which stressed the diagnostic difficulties that may appear in distinguishing HD from peripheral T-ML.