['Poor vitamin D status, i.e. low serum levels of 25-hydroxyvitamin D [25(OH)D], is common in the general population. Prospective epidemiologic data on the association between vitamin D and mortality in oldest old subjects are limited.', 'This study aimed to determine whether 25(OH)D concentrations were prospectively and independently associated with cardiovascular disease (CVD) mortality and all-cause mortality in oldest old subjects.', 'A total of 312 subjects aged 85 years old at baseline (Octabaix study) were followed for 3 years. Sociodemographic and overall geriatric assessment data were collected. Serum 25(OH)D concentrations were used to assess vitamin D status. Data on overall and cardiovascular mortality were collected.', 'The mean serum 25(OH)D levels were 28 ± 30 ng/ml. During the follow-up period, 58 subjects (18.5%) died. Twenty-five of the deaths (8%) were related to CVD. There were no differences in mortality rates according to the different quartiles of vitamin D (p = 0.41 for total mortality and p = 0.86 for CVD mortality).'] Is low serum vitamin D associated with an increase in mortality in oldest old subjects : the Octabaix three-year follow-up study?