Deep-sea water is rich in minerals, e.g., Mg, Ca, and K which have been considered to be associated with prevention of cardiovascular disease. We investigated the effect of deep-sea water on cardiovascular hemodynamics in Kurosawa and Kusanagi-Hypercholesterolemic (KHC) rabbits. Deep-sea water was pumped in the offing of Cape Muroto in Japan and the mineral constituents were refined to a degree of hardness of 1000. Twenty four 4-month-old KHC rabbits were given refined deep-sea water (n=12) and tap water (n=12) for 6 months. Pressure and flow waves at the ascending aorta were recorded under pentobarbital anesthesia. Systolic, diastolic, pulse and mean arterial pressures and total peripheral resistance were significantly lower in the deep-sea water group than in the control group. There were no significant differences in changes in serum lipid levels, plasma renin and angiotensin converting enzyme activities and electrolyte levels except for Mg2+ after the feeding of the water between the two groups. A slight increase in serum Mg2+ level in the deep-sea water group may not account for the inhibition of mild hypertension. From our results, we conclude that deep-sea water could improve cardiovascular hemodynamics, even though the factors which affect the blood pressure are still unknown.