Guillain–Barré syndrome (GBS), a disease affecting the peripheral nervous system, is now well known. However, the disease concept has evolved over successive periods. For example, for approximately nine decades from the first report of GBS, it was considered to have a spinal cord origin. After the first clinical report, the accumulation of detailed clinicopathological data showed that GBS is composed of two distinct clinicopathological entities: acute inflammatory demyelinating polyneuropathy, and acute motor axonal neuropathy or acute motor and sensory axonal neuropathy. Acute inflammatory demyelinating polyneuropathy is characterized by the patchy distribution of demyelinative foci throughout the peripheral nervous system, whereas acute motor axonal neuropathy/acute motor and sensory axonal neuropathy shows primary axonal degeneration in the peripheral nervous system, which is particularly accentuated at the spinal nerve roots. The purpose of the present article was to provide an overview of the previous publications regarding the pathology of GBS and to thereby elucidate the pathological mechanisms of this still threatening disorder from a pathological viewpoint. The critical pathological feature of acute inflammatory demyelinating polyneuropathy is the complement–macrophage‐induced cytotoxic damage on the plasmalemma of the Schwann cells, whereas that of acute motor axonal neuropathy/acute motor and sensory axonal neuropathy is the antibody–complement‐mediated immune attack on the axolemma at the nodes of Ranvier.