Primary central nervous system lymphoma (PCNSL) is a rare form of non-Hodgkin lymphoma, but in recent years the incidence in the immunocompetent population has been increasing. Elderly patients, or those over the age of 60 years, represent an important subgroup and account for over half of PCNSL patients. Treatment of older patients poses a number of challenges, and the optimum approach is yet to be defined. Chemotherapy, particularly with high-dose methotrexate as a single agent or in combination, is the mainstay of treatment of PCNSL. However, chemotherapy is associated with systemic toxicities, such as myelosuppression, to which the older patient is more vulnerable. Radiotherapy is also effective but is limited by significant delayed neurotoxicity, especially in older patients. Most studies support the use of chemotherapy-only treatments for elderly patients given the high risks of neurotoxicity associated with radiotherapy. Nevertheless, the prognosis remains poor regardless of the chemotherapy chosen. This article reviews the principles guiding the treatment of PCNSL in the elderly, identifies the limitations of current studies, and critically reports on the available literature.