Two different types of dementia and corresponding neuropathological findings of patients with human immunodeficiency virus (HIV) infection are presented. In one case, "subcortical" dementia with slow movements and mental processes as well as problems in active recall but without focal defects corresponded to diffuse leukoencephalopathy. In another case, "cortical" dementia with impaired abstraction and memory as well as several focal defects corresponded to microglial nodules in cortical and in deep grey matter, with only a mild diffuse leukoencephalopathy. Thus, in contrast to earlier interpretations, subcortical dementia does not appear to be the only form of dementia in HIV-infected patients, and cortical dysfunction may also occur.