Donor hypernatremia is known to be associated with initial graft dysfunction in liver transplantation. Controversial data exist regarding the impact of sodium dysregulation on patient survival after heart transplantation (HTX). The aim of this study was to investigate the influence of donor sodium levels on survival in a large cohort of heart transplant recipients from the Eurotransplant registry. From 1997 to 2005, all consecutive adult HTX performed in the Eurotransplant region were included into this study (n = 4641 patients). Multivariate analysis was applied to investigate possible clinical predictors for 1-year post-transplant survival after cardiac transplantation (donor sodium levels, donor age, donor cause of death, recipient age, primary disease, urgency status, cold ischemia time). In multivariate analysis, recipients receiving a donor heart with serum sodium level lower than 130 mmol/l or higher than 170 mmol/l had a 1.25-fold higher risk for 1-year post-transplant mortality than patients with normal donor sodium ranges (P = 0.007). Other independent risk factors for impaired 1-year survival were recipient age, the indication for transplantation and the urgency status of the recipient. Our study demonstrates that hyponatremia as well as hypernatremia show a strong U-shaped correlation with poor survival after cardiac transplantation. Accurate donor management to avoid electrolyte disorder seems to be crucial for ensuring good quality of donor hearts.