['To define vitamin D levels and their association with cognition in subjects with exceptional longevity.', 'Cross-sectional.', 'Community and long-term care facilities.', 'Ashkenazi Jewish subjects (n = 253) with exceptional longevity, with comparison made to the Third National Health and Nutrition Examination Survey (NHANES III) participants aged 70 and older.', 'Serum 25-hydroxyvitamin D levels were measured using liquid chromatography/tandem mass spectrometry analysis. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and clock drawing test (CDT: command and copy).', 'The median age of the Ashkenazi subjects was 97 (interquartile range (IQR) 95-104). Age-associated rise in the prevalence of vitamin D insufficiency, defined as a serum vitamin D level of less than 30 ng/mL, was noted in NHANES III (P = .001). In the Ashkenazi group with longevity, the rate of vitamin D insufficiency was comparable with that of the NHANES III participants, who were up to 25 years younger. In the cohort with exceptional longevity, 49% demonstrated cognitive impairment as assessed according to MMSE score (impaired cognition, median 9.5 IQR 0-24); normal cognition, median 29 (IQR 18-30) P < .001). Vitamin D insufficiency was more prevalent in those with impaired cognition, defined according to the MMSE (71.8% vs 57.7%, P = .02) and the CDT copy (84.6% vs. 50.6%, P = .02), than in those with normal cognition. This association remained significant after multivariable adjustment in logistic regression models for cognitive assessments made using the MMSE (odds ratio (OR) = 3.2, 95% confidence interval (CI) = 1.1-9.29, P = .03) and the CDT copy (OR = 8.96, 95% CI = 1.08-74.69, P = .04).'] Do individuals with exceptional longevity manifest a delayed association between vitamin D insufficiency and cognitive impairment?