Coexpression of CD30 and CD15 is typically associated with classic Hodgkin's lymphoma (HL). Peripheral T-cell lymphomas (PTCLs) can often display histologic features that simulate classic HL. However, reports of PTCLs coexpressing both CD30 and CD15 have been infrequently described. We report 11 cases of PTCL in which at least a subset of the neoplastic cells coexpressed CD30 and CD15. The patients included 4 women and 7 men and age ranged from 43 to 83 years (median, 62 years). Nine of 10 patients had advanced stage III or IV disease at presentation. Nodal involvement predominated in 8 of 11 patients, whereas 2 patients presented primarily with skin involvement. Two distinct groups were identified based on morphologic and immunophenotypic features. The first group of 5 cases had histologic features mimicking classic HL with CD30+, CD15+ Reed-Sternberg (RS)-like cells in an inflammatory background of varied extent and composition. The background lymphoid cells showed minimal cytologic atypia. The RS-like cells were negative for CD20 and CD79a in all cases, and CD45 expression was absent in 4 of 5 cases. The RS-like cells expressed CD25 and at least one T-cell-associated marker in all cases. The background T-cell population showed convincing subset predominance in 4 of 5 cases and loss of T-cell-associated antigens in 3 of 5 cases and coexpression of CD30 and CD15 in one case. The second group of 6 cases had morphologic features more in keeping with PTCL than classic HL. The proportion of neoplastic cells coexpressing CD30 and CD15 varied. Loss of T-cell antigens was noted in all cases and CD4 predominated in 4 of 5 cases. Three of the 6 cases expressed CD45. PCR analysis revealed clonal T-cell receptor gamma (TCR-gamma) chain gene rearrangements in 9 of 11 cases, but no immunoglobulin heavy (IgH) chain gene rearrangements. In situ hybridization studies for Epstein-Barr virus were negative in all cases. In some PTCL cases, the overlap with classic HL can be striking, and combined immunophenotypic and molecular studies are often necessary to confirm the diagnosis.