Oxidative stress leads to the production of reactive oxygen species that can attack lipid membranes resulting in cellular dysfunction and death. Cellular redox state is closely linked to ceramide, sphingomyelin, and 4-hydroxynonenal (HNE) levels. We describe data showing increased levels of these oxidative stress markers in HIV encephalitis. In addition, actively progressing HIV dementia is associated with increases in HNE and ceramide, while inactive HIV dementia is associated with increases in sphingomyelin. These markers may be useful for distinguishing between different clinical phenotypes of HIV dementia.