Electrogastroenterography (EGEG) is a method to record electrical activities of the stomach and the intestine using skin electrodes. We investigated whether this method could be used to detect gastrointestinal dysfunction in patients with idiopathic Parkinson's disease. EGEG recordings were done with ten patients with idiopathic Parkinson's disease and ten control subjects before and after a meal. The patients showed changes in EGEG that were markedly similar to those of acute stage of vagotomized patients reported previously. Patients' increase rate in amplitude of gastric activity after the meal (median: 1.19) was significantly (P < 0.05, Mann-Whitney test) smaller than that of the controls (median: 2.84), and normal temporal frequency decrease of gastric activity after the meal was not seen in the patient group. These results suggest vagal nerve dysfunction of patients with Parkinson's disease, though other possibilities could not be denied. EGEG may be useful to assess patients' gastrointestinal dysfunction though we need further study to elucidate the relation between pathophysiology of their symptoms and EGEG findings.