In order to elucidate the role of noradrenergic and dopaminergic activity in the pathogenesis of postprandial hypotension, the effect of feeding of ordinary diet on blood pressure, pulse rate, plasma catecholamine and other circulating vasoactive substances such as insulin were examined in mild essential hypertensive patients (EH) and their age-matched control subjects (N). Mean blood pressure significantly decreased in both N and EH after feeding, and the decrease tended to be greater in EH than in N. Feeding induced a marked increase in plasma norepinephrine in both N and EH. Plasma dopamine significantly increased following feeding was observed in N, while the increase in plasma dopamine following feeding was blunted in EH. The ratio of norepinephrine to dopamine following in EH was significantly greater than that in N. From these results, it is suggested that the feeding-induced stimulation of noradrenergic activity may be a result from the decrease in blood pressure, and that the blunted response of dopaminergic activity in EH may reflect the enhanced conversion of dopamine to norepinephrine probably due to the enhanced activity of dopamine beta-hydroxylase in the sympathetic nerves.