Funding Information No funding information provided.

Objectives: Blood pressure (BP) abnormalities have been known in Parkinson’s disease (PD) patients. The present study aimed at determining how the BPs of PD patients fluctuate in a day. Methods: A total of 37 PD patients and 44 OD (other disease) patients, all of who were inpatients, were monitored every 30 min by 24-h ambulatory blood pressure monitoring (ABPM). Results: The average systolic BP and the number of patients who showed postprandial hypo-tension were not different between the two groups. However, occurrence of nocturnal hypertension, BP fluctuation of over 100 mmHg in a day and BP of over 200 mmHg were significantly more frequently observed in the PD patients than in the OD patients. In the PD patients, these parameters were not different between those who were suffering from the disease for less than 10 years and those with the disease for 10 years or longer, as well as between those who had a Hoehn–Yahr staging scale of 2–3 and those with a scale of 4–5. Conclusion: Twenty-four-hour ABPM, not BP measurement once a day, enables us to deter