A aged fermented milk prepared by culturing with various lactic acid bacteria and a yeast exhibited a significant antihypertensive effect in spontaneously hypertensive rats (SHR) following oral intake. However, the fermented milk showed weak inhibition against angiotensin I-converting enzyme activity in vitro, suggesting that in addition to the direct inhibition of angiotensin I-converting enzyme activity, other mechanisms also participate in the antihypertensive effect of the aged fermented milk in SHR.