Background: Vitamin D deficiency is independently associated with functional impairment in elderly patients and is an independent risk factor for mortality. Objective: To assess the influence of severe vitamin D deficiency on the functional status, falls, fractures, cardiovascular morbidity and mortality and all-cause mortality in elderly nursing home residents. Design: Non-interventional, prospective, observational study. Setting: Nursing home. Participants: Non-dependent elderly. Measurements: Urea, creatinine, cholesterol, triglycerides, calcium, phosphorus, 25-OH vitamin D, parathyroid hormone (PTH), and cystatin C were determined in blood and microalbuminuria in urine. All patients were administered the Katz Index of Independence in Activities of Daily Living (Katz ADL), the Tinetti Balance and Gait Evaluation, lower extremity function tests and the Mini-Mental State Examination. Patients were divided in two groups: those with 25-hydroxyvitamin D <12.48 nmol/l (severe vitamin D deficiency) and those with 25-hydroxyvitamin D ≥ 12.48 nmol/l. Falls, clinical fractures, and cardiovascular morbidity and mortality and all-cause mortality were recorded during the 20-month follow up. Results: Patients with severe vitamin D deficiency were older (87 ± 7 vs. 83 ± 7 yrs., p = 0.025) and more often female (96% vs 4%, p = 0.028) and had lower levels and calcium and albumin and higher levels of PTH, a higher frequency of heart disease (p = 0.02), and worse lower extremity function: Tinetti gait (10 ± 2.39 vs 11.21 ± 1.44, p = 0.034), Tinetti balance (1.83 ± 1.11 vs 2.5 ± 1.19, p = 0.011). These patients had a non-significant higher number of falls and clinical fractures, and significantly greater mortality (29% vs 2%, p = 0.01). Conclusions: Non-dependent elderly nursing home residents with severe vitamin D deficiency have greater mortality, functional impairment of the lower extremities and a trend to a greater number of falls and clinical fractures.