The utility of formulas estimating glomerular filtration rate (GFR) in liver transplant patients has not been well described. The purpose is to determine the correlation between the radionuclide GFR (rGFR) with formulas commonly used to estimate GFR. This study represented a secondary outcome measure of a multicenter randomized trial comparing the effectiveness of two immunosuppressive regimens in adult liver transplant patients (n=148). A total of 68 rGFR were measured, 33 at baseline and at 35 at three months after transplantation. GFR was estimated using 1/Scr and Cockcroft-Gault, MDRD, and Nankivell equations. At both time points assessed, all correlations with rGFR were poor: 1/Scr (r: 0.17 and 0.25), Cockcroft-Gault (r: 0.31 and 0.35), MDRD (r: 0.27 and 0.35), and Nankivell (r: 0.11 and 0.20). Accepted formulas to estimate GFR correlate poorly with rGFR during the first three months after liver transplantation. Recalibration of these formulas is required to improve the estimation of GFR in liver transplant patients.