Objective: Several intervention trials have shown that diet composition affects blood pressure (BP). In this study we focused on postprandial hemodynamic changes on a high carbohydrate versus a high protein diet. Design and Method: In this randomized double-blind parallel group study, 53 adult untreated overweight subjects with mildly elevated BP (BMI 25-35 kg/m2, BP > 130/85 and <160/100 mm Hg) were included. After a 2-week run-in period on a weight-maintaining standardized diet (15 en% protein (P), 30 en% fat (F) and 55 en% carbohydrate (C)), subjects were randomized to a high P or a high C diet for 4 weeks. On the high C diet 60 g of C of the run-in diet was replaced by 3x20 g of maltodextrin supplements, on the high P diet 60 g of C was replaced by 3x20 g of a protein supplement (mixture of 20% pea, 20% soy, 30% egg and 30% milk protein isolate). Supplements were matched for Na, P, K, Ca and Mg content and taken with each meal. Postprandial hemodynamic responses to the diets were determined on day 1 and day 28 of supplement use over 4 hours after meal ingestion. Differences in the postprandial responses between groups were analyzed by ANCOVA with baseline fasting values as covariate.