Lewy body formation has been considered to be a marker for neuronal degeneration, because postmortem studies of Parkinson's disease (PD) patients have shown loss of neurons in the predilection sites for Lewy bodies. We systemically studied the autonomic nervous system in patients with PD. Lewy bodies were widely distributed in the hypothalamus, sympathetic system (intermediolateral nucleus of the thoracic cord and sympathetic ganglia) and parasympathetic system (dorsal vagal and sacral parasympathetic nuclei). The number of neurons in the intermediolateral nucleus was significantly reduced. Furthermore, Lewy bodies were also found in the enteric nervous system of the alimentary tract, cardiac plexus, pelvic plexus and adrenal medulla. These findings indicate that both central and peripheral autonomic nervous systems are involved in the disease process in PD.