Human immunodeficiency virus-associated Guillain-Barré syndrome typically occurs early in HIV infection before AIDS develops. We report a 56-year-old male AIDS patient, who developed overlapping Fisher/Guillain-Barré syndrome despite markedly decreased CD4 cell counts. Serum anti-GQ1b IgG antibody was positive. His condition improved rapidly after immunoglobulin treatment. This indicates that Fisher/Guillain-Barré syndrome may occur even in severely immunosuppressed patients and that anti-ganglioside antibody production is possibly mediated by a T cell-independent process.