ABSTRACT: Importance:The prevalence of cerebral cavernous malformation (CCM) is unknown. Case ascertainment in most previous studies was based on autopsy data or clinical convenience samples, often without detailed clinical or radiologic information. Objective:To determine the prevalence of CCM in a population-based sample of older adults. Design, Setting, and Participants:This prospective imaging study included 4721 participants aged 50 to 89 years who were enrolled between January 1, 2004, and December 15, 2015, in the Mayo Clinic Study of Aging, a longitudinal, population-based study of residents of Olmsted County, Minnesota. An age- and sex-stratified sampling strategy was used to randomly select participants from Olmsted County using the medical records linkage system of the Rochester Epidemiology Project. Participants were invited to undergo brain magnetic resonance imaging (MRI). Of the 4721 participants, 2715 had an evaluable MRI. All images were reviewed by a board-certified neuroradiologist, and MRI reports were searched for the terms cavernous malformation, cavernous angioma, and cavernoma. Two vascular neurologists reviewed MRIs, and potential CCMs were classified using Zabramski classification. Medical records of the identified individuals with CCM were reviewed along with their demographic information, medical history, and any symptoms referable to the identified CCM lesion. Main Outcomes and Measures:Prevalence of CCM and clinical and radiologic characteristics of study participants with CCM. Results:Of the 2715 participants who underwent MRI scans, 12 (0.44%) had CCM. With the use of inverse probability weights to adjust for participation bias, the overall prevalence was 0.46% (95% CI, 0.05-0.86). The age-adjusted prevalence was found to be 0.61% (95% CI, 0-1.47) for the 50- to 59-year age group, 0.17% (95% CI, 0-0.50) for the 60- to 69-year age group, 0.45% (95% CI, 0.09-0.81) for the 70- to 79-year age group, and 0.58% (95% CI, 0-1.29) for the 80- to 89-year age group. The sex-adjusted prevalence was 0.41% (95% CI, 0-1.00) for women and 0.51% (95% CI, 0-1.07) for men. Observed frequencies were similar in men and women, with a slight male predominance. Of the 12 participants with CCM, 9 (75%) had a single Zabramski type 2 lesion in a supratentorial location. Only 1 participant (0.037%) was symptomatic from the CCM during the study period. Conclusions and Relevance:The findings and data from this study are important for determining the potential number of patients available for cohort studies and anticipated clinical trials in older patients with CCM.