This study was performed to clarify the effect of corn soluble dietary fiber(CSD) on blood pressure of human and experimental animals. CSD contained 83.6% soluble dietary fiber. Eighteen subjects received 5 g CSD as a solution of hot water in every meal during 4 weeks. They were divided into two groups by their systolic blood pressure. The groups were mild hypertension group of 6 subjects over 140mmHg and normal group of 12 subjects under 140mmHg, respectively. Systolic and diastolic blood pressures in hypertension group showed significant reduction by the treatment of CSD. However, no significant effect was observed in the normal group. On the other hand, spontaneously hypertensive rats(SHR) were used in the animal experiment. SHR rats were divided into two groups. SHR rats received ad libitum 5% solution in CSD group and distilled water in the control group during 10 weeks. Blood pressure in CSD group was?@ significantly supressed from 1 week after starting the treatment. The specific role of the dietary fiber in the regulation of blood pressure certainly merits more carefully and critical evaluation.