With the increasing success of liver transplantation, more patients are developing late complications such as renal dysfunction. The goal of the current study was to assess the prevalence of renal dysfunction years after liver transplantation and to identify patients at risk for the development of this complication. Of the 527 liver transplantations performed at our institution between April 1990 and October 1998, 353 had pretransplantation and posttransplantation glomerular filtration rate (GFR) determinations by iothalamate clearance. From this entire group, 198 patients had actual 4-year follow-up and 52 had actual 6-year follow-up. In addition, 191 of these patients had intensive follow-up with GFR measurements pretransplantation and at 1 and 3 years posttransplantation (complete follow-up group). All patients received either tacrolimus- or cyclosporine-based immunosuppression. The overall mean GFR levels in both of these groups was acceptable and was not different in cyclosporine- versus tacrolimus-based immunosuppressive regimens. Renal dysfunction was progressive, with 27.5% of patients in the intensive group having a GFR < 40 mL/min/body surface area 5 years after transplantation. GFR pretransplantation did not correlate well with late renal function; however, GFR at 1 year identified patients with subsequent renal dysfunction. The cumulative incidence of renal failure for the entire group was 6.25% at 7 years and 10% at 10 years. Renal dysfunction is a major late complication after liver transplantation. The GFR at 1 year correlates best with late renal function. Patients with a low GFR at 1 year (< 40 mL/min/BSA) are a high-risk group that might benefit from early therapeutic interventions aimed at preventing subsequent renal failure.