Specialists of many profiles are engaged in AIDS investigations. 40-90% of patients present with neurological symptoms. Computer-aided tomography (CT) and magnetic imaging (MR) help assess the brain status, but the semiotics of brain involvement in this infection and the potentialities of these methods are little known. Published reports are miscellaneous and contradictory. This report describes CT and MR manifestations of morphological variants of the disease: HIV encephalopathy, subacute encephalitis, vasculitis, meningitis, tumors, and progressive multifocal leukencephalopathy. Semiotics of opportunistic toxoplasmosis, cryptococcosis, herpes, papovavirus, and cytomegalovirus infections is analyzed. Relationship between immunity disorders and formation of CT and MR picture of brain involvement is discussed. Approaches to improvement of diagnosis and differential diagnosis by novel methods: functional magnetic resonance tomography, magnetic resonance spectroscopy, and positron emission tomography, are outlined.