OBJECTIVE: In the gastrointestinal neural system, the emergence of Lewy Body (LB) is usually earlier than the clinical diagnosis of Parkinson (PD) motor symptoms. Therefore, this study is aimed to explore whether the LB in the gastrointestinal tract of prodromal PD patients. PATIENTS AND METHODS: 98 paraffin embedded tissue specimens from 57 PD patients were collected in the Second Affiliated Hospital of Soochow University archives, as well as 98 tissue specimens of 90 non-PD patients undergone surgical resection. The pathological sections were stained by the immune-histochemistry method. The positive staining of aggregated alpha-Synuclein (a-alpha-syn) and phosphorylated alpha-Synuclein (p-alpha-syn) in gastrointestinal tract were counted to analyze the distribution of the expression of a/p-alpha-syn in the prodromal PD patients before diagnosis (0-5 years, 6-10 years, 11-20 years). RESULTS: According to results from the immunohistochemical staining of a/p-a-syn, 35 (52.23%) and 30 (44.78%) tissue blocks were positively stained respectively in total 67 tissue blocks provided from 39 prodromal PD patients. And there were 46 (46.94%) and 25 (25.51%) positive staining in 98 tissue blocks from the control group. In 31 tissue blocks collected from 18 PD patients, there were 19 (61.29%) and 15 (48.39%) tissue blocks with the a/p-alpha-syn positive staining. Compared with non-PD patients from the control group, the a-alpha-syn positive rate was not significantly increased in the pre-and post-diagnosis PD patients (p>0.05). However, p-alpha-syn of both groups increased significantly (p<0.05). Also, the positive expression rate of a/p-alpha-syn in the 6-10-year group was lower than that in the 0-5-year and 11-20-year, and the positive rate of the 0-5-year group was the highest (p<0.05). CONCLUSIONS: p-alpha-syn as the main component of Lewy body of nervous system in the gastrointestinal track may be used as a characteristic predictive marker of PD and the prevention of PD disease.