In isolated liver transplantation pretransplant renal failure is a major mortality risk, there are no guidelines at the moment to establish the indications for a combined liver-kidney transplantation (LKT). In irreversible chronic renal failure (CRF) not on dialysis, nephrological evaluation is required to assess the need for a simultaneous kidney transplantation. There are no experiences about the functional contribution of native kidneys post-LKT. Herein we have reported the case of two patients who underwent LKT in 2004 due to CRF, not yet on dialysis. At the moment of LKT, the first patient (polycystic kidney disease) had a glomerular filtration rate (GFR) = 29 mL/min, and the second recipient (vascular nephropathy and diabetes), a GFR = 33 mL/min. In both cases we did not observe delayed graft function. At discharge the serum creatinine was 1.1 and 1.0 mg/dL, respectively, which was maintained during follow-up. In both cases renal scintigraphy with Tc-99 DMSA was performed to evaluate the functional contributions of transplanted versus native kidneys. In the first case scintigraphy at 9 months after LKT demonstrated an 81% contribution from the transplanted kidney, 9% from the right and 10% from the left native kidneys. In the second case, at 3 months after LKT, the functional contributions were 76%, 10%, and 14%, respectively. The transplanted kidney nephron mass may avoid the need for hemodialysis in the early posttransplant period; in the midterm it may help to maintain residual renal function. As in other combined transplant programs (heart-kidney, kidney-pancreas) with irreversible CRF, a GFR < or = 30 to 35 mL/min may be an indication for LKT, but we need more experience.