Background: Changes in blood pressure (BP) over time have not been considered in investigations on the relationship between BP and cerebrovascular disease (CVD). Objective: To investigate BP changes throughout a 24-hour period in lacunar infarct patients with different outcomes. Methods: Twelve control subjects (group 1) and 56 patients with symptomatic lacunar infarcts were studied. The infarct patients were divided into three groups: group 2, 25 patients with a fair outcome without any cerebrovascular attack or progressive dementia (mean follow-up period: 4.4 years); group 3, 14 patients with worsening of clinical dementia rating and silent lesions, which included lacunae and diffuse white matter lesions (4.5 years), and group 4, 17 patients who developed symptomatic infarcts (1.7 years). MRIs and ambulatory BP monitoring were performed for each patient on two separate occasions. No patient was treated with antihypertensive agents during the course of the study. Results: In group 2, the second measurements were significantly higher than the first for 24-hour systolic BP (SBP), daytime SBP, 24-hour diastolic BP (DBP), daytime DBP (p < 0.01, for all) and nighttime DBP (p < 0.05). In group 3, the second measurements were significantly lower than the first for 24-hour SBP, daytime SBP, 24-hour DBP, and daytime DBP (p < 0.01, for all). In group 4, the second measurements were significantly lower than the first for 24-hour SBP and daytime SBP (p < 0.01). The correlation between BP and pulse rate became positive for group 2 in second measurements, but was not positive for groups 3 and 4. Conclusions: BP tended to elevate over time in patients with a fair outcome. In contrast, BP tended to decrease in those who developed dementia and symptomatic infarct. Autonomic functions including sympathetic activity might play a role in changes in BP in lacunar infarct patients during the course of disease.