Ecklonia cava is brown alga which ow in the sea all over the world. It has been shown that Ecklonia cava has antioxidative, anticoagulant, and antiviral effect, lately. In this study, we examined the antihypertensiye effect of Ecklonia cava extract (Eca) on 2-kidney 1-clip Goldblatt Hypertensive Rats (GB-HT). In vitro assay, the angiotensin converting enzyme (ACE) activity was significantly inhibited by Eca (27-95% inhibition at $10-50;{mu}g/ml$). The systolic blood pressure of Eca-treated GH-HT significantly was decreased compared to that of control CB-HT (15% decrease at 50 mg/kg). The serum ACE activity was also inhibited 19% with 50 mg/kg Eca treatment. These results suggest that Eca can be used as antihypertensive functional foods and nutraceuticals.