Objective: To assess the association between poor physical function, cognitive dysfunction, and high nocturnal blood pressure (BP) level, all of which are markers of vulnerability or frailty in elderly persons. Design: Cross-sectional study. Methods: In 148 treated elderly hypertensive patients (mean age: 75.5 years; 30% men), who were ambulatory, lived independently, and were not nursing home residents, we evaluated 24-hour BP levels, physical function test (walking speed and timed up-and-go tests), cognitive function test (mini-mental state examination: MMSE), and carotid-artery intima-media thickness (IMT). Results: Both slower walking speed and lower MMSE scores were significantly associated with high nocturnal BP level (β=−0.236 and −0.261, respectively; both P Conclusion: Poor physical function in patients taking antihypertensive medications, particularly in those with concomitant cognitive dysfunction, could be valid markers likely to be associated with high nocturnal BP level. Because a high nocturnal BP level under antihypertensive treatment is the most potent predictor of cardiovascular outcome, our findings have important clinical implications, i.e., that treated elderly hypertensives who experience poor physical function and/or cognitive dysfunction might be in a state of high cardiovascular risk requiring 24-hour BP control, especially nocturnal BP control.