Swallowing disorder is common in Parkinson's disease (PD). We studied the swallowing disorder in PD, and tested the efficacy of Banxia Houpo Tang (BHT, a Chinese traditional medicine) in improving the swallowing reflex of PD patients. The Swallowing reflex test is a simple method used to detect swallowing disorders in patients with cerebrovascular disease. Because we observed previously that BHT significantly improved the swallowing reflex in cerebrovascular patients, we studied whether BHT was also effective in improving the swallowing disorder in patients with PD. 23 PD patients (13 males, 10 females, mean age 66.0+/-9.3, Hoehn & Yahr (H-Y) mean score = 2.8) were evaluated for swallowing reflex and the concentration of substance-P in their saliva before and after 4 weeks of BHT treatment. The swallowing reflex before treatment was significantly delayed, according to the H-Y score (Spearman's p = 0.014, R2 = 0.463). The swallowing reflex before BHT treatment was 3.66+/-0.98 sec, and after BHT treatment, it improved significantly, to 2.27+/-0.54 sec (p < 0.0001). Substance-P concentration in PD patients saliva before treatment was significantly lower than in healthy controls (p = 0.007), but showed no significant change after BHT treatment. Our research shows that the swallowing reflex is an effective method to evaluate the swallowing disorder in PD. BHT can significantly improved the swallowing reflex in PD patients, and therefore can be a hopeful candidate for preventing aspiration pneumonia in PD.