The cardiovascular and plasma catecholamine responses to oral glucose (50 g) ingestion were investigated in five elderly subjects with orthostatic hypotension and five elderly control subjects. All the orthostatic hypotension subjects showed blood pressure falls after glucose ingestion, as compared to only one of the control subjects. Significantly greater falls in the orthostatic hypotension as compared to control patients were observed for systolic blood pressure (P less than 0.01) at 60 and 90 min following glucose and mean blood pressure (P less than 0.05) at 60 min following glucose. The orthostatic hypotension subjects did not have evidence of reduced heart-rate or plasma catecholamine responses to the glucose ingestion. It is concluded that, in elderly patients with orthostatic hypotension, disorder of blood pressure control may also cause hypotension associated with eating.