Before the introduction of highly active antiretroviral therapy (HAART), human immunodeficiency virus (HIV)-related primary central nervous system lymphoma (PCNSL) represented one of the most prevalent causes of focal brain lesions in HIV-infected people. The prognosis of PCNSL was very poor, with median survival time not exceeding 2 months. Brain biopsy was the method of choice for the definitive diagnosis, but it was and remains an invasive procedure with morbidity and mortality as well as considerable costs in terms of patients' management and quality of life. The strict association between AIDS-PCNSL and Epstein-Barr virus led to the suggestion that EBV DNA in cerebrospinal spinal fluid (CSF) might serve as a diagnostic marker, reducing the time required for diagnosis and allowing a minimally invasive approach. The clinical usefulness of this methodology has been largely demonstrated through clinical practice. After the introduction of HAART in clinical practice, a survival benefit has been observed for most persons with acquired immunodeficiency syndrome (AIDS)-associated opportunistic infections and cancers. In particular, for patients with non-Hodgkin lymphoma, a higher likelihood of response to chemotherapy as well as a longer survival has been found as a consequence of the use of combined antiretroviral therapy. Although larger studies did not show significant changes in survival of HIV-infected patients with PCNSL in the era of HAART, small case series and anecdotal reports showed the benefit of HAART in the treatment of PCNSL. Nevertheless, these patients' survival still remains very poor and it could be hypothesized that, other than specific cancer prognostic determinants and severe immunodeficiency, viral pathogenesis as well as EBV-specific immunologic dysfunction may be responsible.