Abstract: The long-term use of calcineurin inhibitors (CNI) leads to renal dysfunction in many liver transplant (LT) recipients. The purpose of this analysis is to evaluate renal function in patients converted from CNI to sirolimus (SRL). From May 2002–November 2006, 137 LT were performed in 125 patients, 72 of which were converted to SRL. Evaluation of SRL conversion was stratified by early conversion (<90 d from LT) (EC) vs. late conversion (LC). Renal function was evaluated using the six-point modification of diet in renal disease formula (estimated glomerular filtration rate [eGFR]). Forty-two patients on SRL and 40 on CNI had at least three months of follow-up and are included in the eGFR evaluation. At all time points after conversion, the EC group demonstrated a significantly higher mean eGFR than those in the LC group. A significant improvement in eGFR was seen within the EC group when comparing eGFR at time of conversion to eGFR at three, six, nine, and 12 months after conversion and last follow-up. The only improvement in the LC group was from conversion to the three-month time point. We conclude that EC to SRL results in a profound improvement in eGFR that begins at three months and is sustained beyond one yr.