Venous responses to stabilized orthostasis (45 degrees head-up tilt) were studied in seven normotensive subjects and eight hypertensive patients, when on high and low dietary sodium intake. Exchangeable sodium and blood volumes were determined to permit correlation with any significant changes in venous behavior. The intent of this study was to detect and analyze any diet-induced changes in responses of forearm veins to prolonged orthostasis. The pharmacological effects of sodium depletion by medication and diet on arteries and veins of hypertensives are discussed. The results of this study indicate that dietary sodium depletion did not have adverse effects on the ability to maintain stabilized venous tone during orthostasis. These results support recommendations that moderate dietary sodium restriction be included as part of antihypertensive regimens.