Primary central nervous system lymphoma (PCNSL) describes a malignant non-Hodgkin's lymphoma (NHL) whose sole site of involvement is the central nervous system (CNS). The diagnosis of PCNSL must be differentiated from systemic NHL with metastasis to the CNS, which usually occurs late in the course of systemic disease. PCNSL accounts for approximately 4% to 7% of primary brain tumors, and its incidence has been increasing since the mid-1970s. Compared with other more common malignant primary brain tumors, PCNSL tends to be more amenable to radiotherapeutic and chemotherapeutic intervention. In this article, the authors review the standard treatment for upfront and recurrent PCNSL.