 Despite significant therapeutic improvements, congestive heart failure CHF patients still have a poor prognosis. Currently, 5-year survival rates are only 35-50. There is an accumulating body of evidence from prospective cohort studies that low circulating 25-hydroxyvitamin D is an independent predictor of all-cause and cardiovascular mortality, respectively. Vitamin D deficiency is prevalent among CHF patients. We hypothesize that vitamin D may improve survival in CHF patients. We therefore aimed to investigate whether vitamin D supplementation reduces mortality and increases event-free survival in end-stage CHF patients. 