The aim of this study was to assess the reflex and oral, pharyngeal, esophageal phase of swallowing in patients with Parkinson's disease (PD). Eighteen patients with PD and 22 healthy control subjects were investigated using electromyography (EMG) and esophageal scintigraphy. This study demonstrated delayed triggering of the swallowing reflex (443+/-84 ms in patients with PD vs. 230+/-96 ms in controls, p<0.05) and prolongation of laryngeal movement (980+/-140 vs. 649+/-145 ms, p<0.05). We found prolongation of the esophageal phase of swallowing (14.46+/-5.30 vs. 7.45+/-1.64 s, p<0.001) in PD patients. The dysphagia limit i.e. the maximum amount of water swallowed at once was smaller in PD patients than in controls (6.23+/-3.67 vs. >20 ml). Dysphagia was observed in all patients studied although only 13 of them complained about it. In the remaining five cases swallowing impairment was subclinical and it consisted of decreased dysphagia limit and prolongation of the esophageal phase. Dysphagia at the subclinical level may be one of the early symptoms of PD.