We describe a case of primary anaplastic diffuse large-cell lymphoma arising in the central nervous system (CNS). Primary CD30-positive anaplastic diffuse large B-cell lymphoma of the brain is very rarely reported. Given that this tumor is immunohistochemically heterogeneous, polymerase chain reaction (PCR) and Epstein-Barr virus (EBV) analysis of tumor DNA are essential techniques for early and accurate histological diagnosis in these CD30-positive cerebral lymphoma cases. We report an early CD30- and EBV-positive anaplastic diffuse large B-cell lymphoma in the CNS that was diagnosed not only from the immunohistochemical study and MRI findings, but also from the genotype confirmations. This tumor was documented to have EBV episomes of monoclonal origin by PCR analysis of immunoglobulin gene rearrangement.