Technical Abstract: Whole grain foods have been reported to lower blood pressure, but results have been mixed. It has not been determined whether fiber content or type of fiber of the grains is responsible for this beneficial effect. The objective of this study is to compare the effects of predominantly insoluble fiber grains (whole wheat/brown rice) & soluble fiber grain (barley) on cardiovascular risk factors in a whole grain diet. Eighteen non-hypertensive men (28-62 yr) with moderately elevated total plasma cholesterol levels were selected for the study after an initial clinical screening & medical evaluation. The study was approved by the Institutional Review Board of the Johns Hopkins School of Public Health. Men consumed a controlled step 1 diet (30% fat, 55% carbohydrate, 15% protein, < 300 mg cholesterol) for 2 wk. After the initial period, men consumed diets in which about 20% of energy was replaced with brown rice/whole wheat, barley, or ½ barley & ½ brown rice/whole wheat for 5 wk each in a Latin square design. Blood pressure was determined weekly before breakfast. Urinary excretion of Na, K, P, Ca, Mg, uric acid, creatinine, urea nitrogen, and glucose were determined from 72-hr urines collected at the end of each diet period. Systolic, diastolic, and mean arterial pressure did not change during the step 1 diet, but were significantly reduced by whole grain diets whether the fiber source was predominantly soluble (barley) or insoluble (brown rice & whole wheat). Urinary excretion of potassium, phosphorus, and urea nitrogen were lower after consumption of the high barley diet. Increasing whole grain foods in a healthy diet can reduce cardiovascular risk.