Ambulatory arterial stiffness index (AASI) is associated with microvascular damage in other organs, but the association with microvascular brain damage is unknown. The association of AASI with magnetic resonance imaging (MRI) markers of cerebral small vessel disease in 143 patients with lacunar stroke was investigated. We performed 24-hour ambulatory blood pressure monitoring and scored the presence of lacunes, white matter hyperintensities, perivascular spaces, and cerebral microbleeds on brain MRI. In logistic regression analyses, AASI was associated with white matter hyperintensities, but, after adjustment for age and sex, this association lost significance. AASI was not associated with lacunes, microbleeds, or perivascular spaces. Systolic and diastolic 24-hour blood pressure values were associated with lacunes, perivascular spaces, and microbleeds independent of age and sex. Despite its significance and growing interest as a possible prognostic and therapeutic target in (micro)vascular diseases, AASI seems to have no added value over standard 24-hour blood pressure in cerebral small vessel disease.