Guillain-Barré syndrome and other neurologic syndromes occur rarely as complications of viral hepatitis, although a causal association has not been established. Seven cases of serologically documented hepatitis A have been reported with Guillain-Barré syndrome; all recovered, with mild neurologic residua in four. Eight cases of serologically documented acute hepatitis B have been reported with Guillain-Barré syndrome; all recovered, with mild neurologic residua in two. In one case, immune complexes of hepatitis B surface antigen and its antibody were present in the cerebrospinal fluid. Other neurologic syndromes have also been reported in patients with serologically defined viral hepatitis, including mononeuritis, auditory neuritis, and seizures. Chronic hepatitis B and mononeuritis multiplex are found together in 31-54% of patients with periarteritis nodosa. The mechanisms for these associations are unknown, but may include direct cytotoxicity of the virus or immune-mediated damage. Vasculitis of the vasa nervorum plays an intermediate role in at least some cases.