The present case was an elderly man with a history of gastric cancer, diffuse biliary duct stenosis and liver cirrhosis. He had markedly elevated IgG, suggesting chronic infection or inflammatory changes in the biliary duct. He developed weakness in his arms and became unable to use his hands within one month and 2 weeks later, he had difficulty walking. Based on his progressive disease course, elevated serum IgG, nerve conduction study and enhanced MRI findings, we diagnosed him as suffering from immune-mediated subacute polyradiculoneuropathy with polyclonal gammopathy, which might be related to Guillain-Barré syndrome. Intravenous immunoglobulin (IVIg) was dramatically effective in this patient. In the follow-up 6 months later he was stable and could walk without a cane. Even in patients with polyclonal gammopathy in chronic inflammatory disease of another organ, IVIg may be effective and beneficial for the patients's quality of life.