Acquired immunodeficiency syndrome has had a major impact on all aspects of clinical neuroscience in the past few years. Thus understanding acquired immunodeficiency syndrome and its associated complications within the nervous system was a major component of this review of the past year's radiologic literature of infection in the central nervous system. Particular topics discussed include the appearance of primary human immunodeficiency virus infection of the brain as well as toxoplasmosis, cryptococcal infection, and progressive multifocal leukoencephalopathy. In addition, the association of acquired immunodeficiency syndrome with the appearance of lymphoma, myeloradiculopathy, and vascular disease are considered. The remainder of the literature on central nervous system infection in the past year generally concerned the imaging characteristics of unusual infections such as cysticercosis, paragonimiasis, tuberculosis, Lyme disease, viral infection, and nonspecific inflammation of the meninges. The availability of an MR imaging contrast agent (gadolinium) also provided important diagnostic information to the radiologist in the imaging of infection in the central nervous system.