OBJECTIVE: To investigate the change in systolic blood pressure (SBP) induced by meals and to compare their impact on the orthostatic SBP response in elderly Parkinson's disease with that in control patients. DESIGN: Ten elderly patients suffering from Parkinson's disease were compared with 10 age-matched elderly control patients. METHODS: The postprandial SBP change was measured by means of ambulatory blood pressure monitoring with the patient in the supine position. Orthostatic SBP responses were measured the next day by means of active standing and passive head-up tilting tests performed before and after the patients had their lunch. RESULTS: In Parkinson's disease patients, a postprandial SBP drop of 27 mmHg in the supine position was found compared with a drop of 8 mmHg in controls. In Parkinson's disease patients, that drop was moderately correlated to the orthostatic SBP responses and significantly correlated to the preprandial supine baseline SBP level. The orthostatic fall in SBP was greater with passive than with active standing and with both it was greater in Parkinson's disease patients than in the control subjects. The fall in orthostatic blood pressure was reduced by a previous meal. In contrast, there was no difference in orthostatic heart rate responses between the patients and the controls. CONCLUSIONS: Parkinson's disease patients demonstrated a significant postprandial drop in SBP and a tendency towards orthostatic hypotension, which was not worsened by the meal, probably owing to a stronger sympathetic activation. Postprandial supine SBP change and orthostatic SBP responses were only moderately associated in Parkinson's disease patients. In addition to autonomic dysfunction, an increased baseline SBP level might contribute to both phenomena.