Clinical studies indicate that indices of glomerular filtration rate (GFR) as serum creatinine or creatinine clearance can predict the risk of death in congestive heart failure (CHF) and in heart transplantation. The study reports data on creatinine clearance before and after heart transplantation in 160 patients followed-up for 5 years at our Unit. Pre-transplant creatinine clearance averaged 83.5+/-32 mL/min x 1.73 m(2) and was not significantly associated with 5-year mortality. Creatinine clearance significantly decreased after heart transplantation with a linear trend up to 3 years for patients with complete follow-up. Data suggest that the relation between kidney function and mortality after heart transplantation is affected by several confounders with inclusion of cause of heart disease, co-morbidity, anemia, and post-transplant decrease in kidney function.