Neurological complications may occur even before immunosuppression is clinically observed, and can thus reveal HIV infection. Aseptic meningitis, subacute encephalitis, vacuolar myelopathy, inflammatory myopathy, and different types of polyneuropathies seem to be associated with HIV, but their pathogenesis has only recently begun to be understood. These complications must be distinguished from opportunistic infections and from intra-cerebral tumors with which they often coexist. The Sixth International Conference on AIDS in San Francisco has defined the extent and limits of our present knowledge, and has given new directions for research in this last, but not least important chapter of modern neurology.