BACKGROUND: It has been reported that the association between blood pressure and cognitive impairment could be modified by factors such as gender, education, and Apo E genotypes. This study was aimed to investigate whether `age' could also be a modifier of the association. METHODS: The study group consisted of 489 participants aged 65 years or over who lived in Namwon, Korea. The presence of hypertension was ascertained by the measurement of their resting blood pressure. A cognitive impairment was considered to be present when a Korean Mini-Mental State Examination score was less than 19 (30th percentile). RESULTS: A higher systolic blood pressure was significantly associated with cognitive impairment, after an adjustment for age, gender, education, and occupation. However, the significance was lost in subjects aged 71 or over. CONCLUSIONS: High systolic blood pressure is a factor strongly associated with cognitive impairment in an aged population. However, in the subjects with far advanced age, the association is not significant. Further studies are required to elucidate whether blood pressure lowering strategies should be differentiated according to age in order to reduce cognitive impairment.