Several studies have shown a relationship between BISH and cerebrovascular events, but no studies have investigated a relationship with cognitive function. The aim was to assess the cognitive function in the elderly with recent BISH. According to WHO Guidelines (1999), we selected 10 elderly normotensives, 10 elderly with recently diagnosed (<2 years) BISH, and 10 elderly with recently diagnosed (<2 years) isolated systolic hypertension (ISH). They were submitted to 24-hr ambulatory blood pressure (BP) monitoring (ABPM) and to cognitive assessment by mini mental state examination (MMSE) and the recording of brain ERP, of type N2 and P300. The elderly with BISH, compared to normotensives, showed N2 wave latency values significantly higher, but similar P300 potential latency values and MMSE scores. The elderly with ISH showed N2 and P300 latency significantly higher than the normotensives. The gradual increase of the ERP latency values of the BISH and ISH elderly, in comparison to the normotensives, seems to indicate a gradual alteration of the cognitive processes related to the increase of BP.