Herpesvirus Macaca arctoides (HVMA), an Epstein-Barr virus (EBV)-related herpesvirus of macaque origin, induces malignant lymphomas in rabbits. To get more insights into the oncogenesis of the EBV/HVMA infection the aim of the present study was to prove the in vitro transforming ability of HVMA for rabbit lymphocytes as well as human umbilical cord blood lymphocytes. As a result, B-cell transformation could be demonstrated after infection with HVMA in all mononuclear cell samples of 20 rabbits. The transformation was evaluated microscopically and confirmed by the expression of EBV-related nuclear antigens. The transforming activity led to the establishment of permanent rabbit lymphoblastoid cell lines cultured up to more than 90 passages. The cell lines contained EBV-like HVMA-DNA. Interestingly, the transformed rabbit lymphocytes showed chromosomal abnormalities with a subtetraploid karyotype. The low extent of lytic cycle-dependent expression of virus capsid antigen in the established cell lines increased after treatment with the inducing agents iododeoxyuridine and mitomycin C. In contrast, no transformation could be induced after exposure of human umbilical cord blood lymphocytes to HVMA. The permanent rabbit lymphoblastoid cell lines provide a model for further studies on the role of EBV/HVMA in oncogenesis of lymphomas. In addition, it might be suitable for testing potential antiviral compounds in vitro.