Parkinson’s disease (PD) is associated with a high incidence of dysphagia. Aspiration pneumonia due to dysphagia is a major cause of death in patients with PD, and therefore accurately evaluating dysphagia should help improve prognosis. It has been reported that the severity of dysphagia does not always correlate with the Hoehn and Yahr (H&Y) stage for classifying PD severity. However, no reports have quantitatively evaluated the relationship between severity of dysphagia and H&Y stage. High-resolution pharyngeal manometry (HRPM) is a quantitative method that can be used to measure swallowing pressure from the velopharynx to the entry of the upper esophageal sphincter (UES). We used HRPM to measure swallowing pressure in 51 patients with PD. As PD progresses, atrophy and degeneration of the pharyngeal muscles become more pronounced, which contributes to dysphagia. However, thus far there is no quantitative clinical evidence for this pathological change. To evaluate the relationship between severity of underlying PD and dysphagia, patients were categorized by H&Y stage, as follows: stage II in four patients, stage III in 23, stage IV in 14, and stage V in 10. In patients with H&Y stages II, III, IV, and V, the respective velopharyngeal pressures were 179.8 ± 32.5, 157.6 ± 62.2, 172.2 ± 48.9, and 107.4 ± 44.0 mmHg, the mesopharyngeal pressures were 126.8 ± 53.2, 121.6.1 ± 50.4, 142.1 ± 57.8, and 61.4 ± 19.6 mmHg, the residual UES pressure were -8.0 ± 10.8, 10.3 ± 16.1, 16.5 ± 37.9, and 11.2 ± 16.2 mmHg, and the resting UES pressure were 49.5 ± 30.0, 15.8 ± 25.7, 1.85 ± 14.1, and -1.2 ± 12.2 mmHg. Patients with severe PD demonstrated significantly decreased velopharyngeal and oropharyngeal pressures, along with incomplete UES opening and contraction. HRPM can detect subtle abnormalities by quantifying swallowing pressure in patients with PD. Evaluating swallowing pressure with HRPM provides insights into neuromuscular dysfunction that causes abnormal pressure generation during pharyngeal swallowing in patients with PD.Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.