Increased serum ferritin is frequent in renal transplant recipients. This reflects iron overload due to blood transfusions given to treat renal anaemia. Previous studies suggested excess mortality in non-renal transplant recipients with iron overload. We hypothesized that serum ferritin levels above 1100 ng/ml may be associated with increased long-term mortality in renal transplant recipients. Twenty consecutive renal transplant recipients with high levels of serum ferritin and 20 renal transplant recipients with normal serum ferritin levels, matched for age and gender, were prospectively studied for 10 years. Nine patients (45%) with increased serum ferritin died during follow-up, compared to four controls (20%). Univariate and multivariate analysis identified multiple blood transfusions (>40 units) prior to transplantation as being associated with higher mortality in renal transplant recipients (risk ratio (RR): 3.1, confidence interval (CI): 1.1-9.2; P=0.03). These data suggest that serum ferritin levels above 1100 ng/ml due to multiple blood transfusions causing iron overload is a relevant factor that increases mortality.