A case of relapsing polyneuritis in a cirrhotic woman with a surgical splenorenal shunt is reported. The ultrastructural study of the nerve biopsy shows widespread segmental demyelinization with total myelin breakdown in most fibers; some Schwann cells are invaded by mononuclear cell processes. Such histological changes are characteristic of the Guillain-Barré syndrome. Alcohol and diabetes are unlikely to be the causative factors of the nerve damage. The possible role of unidentified toxic metabolites such as those which cause portosystemic encephalopathy, also present in our patient, is discussed