This article is a brief review of the radiologic-pathologic correlation of central nervous lesions occurring in patients with AIDS. The major discussions of the imaging appearance and radiologic differential diagnosis have been presented elsewhere in this issue. Our emphasis is on the gross pathologic correlations that are only possible with autopsy materials. We will illustrate the opportunistic neoplasms such as primary CNS lymphoma. This article also discusses the imaging and pathology of the common opportunistic infections. Toxoplasmosis, an obligate intracellular protozoan, is the most common CNS infection producing a mass lesion in AIDS. However, AIDS encephalitis, a direct infection of the brain by the HIV-1 virus itself, may actually be more prevalent. Other viral infections occurring in AIDS include progressive multifocal leukoencephalopathy. Fungal diseases infecting the central nervous system of AIDS patients include cryptococcus, aspergillosis, and mucormycosis. The primary purpose of this article is to demonstrate how the gross pathology correlates with the radiologic images.