Clinical, radiological and manometric studies on 27 patients with multiple system atrophy (MSA) were performed to investigate the characteristics of dysphagia. Patients of MSA were divided into 4 groups: 9 patients of OPCA I (duration < 5 years), 6 patients of OPCA II (duration > or = 5 years), 8 patients of SDS (duration < 5 years) and 4 patients of SND (duration < 5 years). A clinical history was taken to distinguish the two types of dysphagia, that is to say, swallowing disturbance in a narrow sense and passage disturbance. In the radiological study, each phase of swallowing was observed by X-rays with contrast medium (Dionosil). In the manometric study, intraluminal resting pressure in the esophagus and pressure of esophageal contraction after swallowing were measured. The results were as follows: 13 patients (OPCA I 2, OPCA II 6, SDS 2, SND 3) experienced the sensation of swallowing disturbance in a narrow sense and 4 patients (OPCA I 1, OPCA II 1, SDS 1, SND 1) had the feeling of passage disturbance. X-ray studies showed 6 patients (OPCA I 0, OPCA II 1, SDS 1, SND 4) had disturbance of lingual movements, 11 patients (OPCA I 1, OPCA II 5, SDS 3, SND 2) had pooling in piriformis sinus and 14 patients (OPCA I 3, OPCA II 4, SDS 5, SND 2) had slight dilatation of the lower esophagus. In the manometric study, 12 patients (OPCA I 4, OPCA II 4, SDS 3, SND 1) were shown to have low intraluminal resting pressure of the upper esophageal sphincter.(ABSTRACT TRUNCATED AT 250 WORDS)