The purpose of this study was to determine whether the stress of caregiving for the Alzheimer's disease (AD) patient accelerates the likelihood of exceeding hypertensive blood pressure (BP) criteria in periodic longitudinal home assessments. In this cohort study, participants consisted of spousal caregivers of AD patients (n = 144) and demographically equivalent non-caregiving controls (n = 47). Thirty percent of caregivers and 33% of controls were receiving antihypertensive treatment at study entry. Supine systolic and diastolic blood pressure (SBP and DBP) was assessed by semi-automated recordings taken in the home every 6 months for 2 to 6 years. Survival analyses (Cox proportional hazards models) were used to determine whether the hazard for developing hypertension (DBP>140, SBP>90) was greater in caregivers than in controls, and whether increased hazards were related to background characteristics or the extent of caregiving demands. Based on periodic 6-month assessments of BP over 6 years, the hazards of meeting criteria for borderline hypertension were greater for caregivers than for controls (Cox Proportional Hazards, chi2 [1, N = 174] = 4.86, p = 0.03). This difference remained statistically significant (p<0.05) after controlling for age, gender, education, socioeconomic status, body mass index, and use of antihypertensive medications. Increased risk of hypertension was not related to the extent of daily living assistance provided, patient problem behaviors, or caregiver distress. The chronic stress of caring for an AD spouse may have adverse effects on blood pressure; however, the mechanism for this relationship remains unclear.