This study explored the relationship between cognitive function and blood pressure (BP) in 84 women and 64 men, aged 55-79. Assessments were made of casual BP, 24-hour ambulatory BP, and cognitive function. Participants had no evidence of any health disorders, were taking no medication, and were primarily normotensive. By means of principal components analysis, the number of variables was reduced to three BP components of Level, Wake Variability, and Sleep Variability and four cognitive components of Psychomotor Speed/Cognitive Flexibility, Attention, Verbal Memory, and Short-term/Working Memory. Elevated ambulatory BP (level and variability) was associated with difficulties in Attention and Short-term/Working Memory. The fact that increased risk of poorer cognitive function may be related to BP in an elderly population with relatively low BP means that even moderate elevations in BP may be cause for concern.