['Renal dysfunction, primarily related to long-term use of calcineurin inhibitor-based immunosuppression, is the most common complication after liver transplantation.', 'To evaluate whether liver transplant recipients with impaired kidney function at transplantation can benefit from early conversion to mammalian target of rapamycin inhibitor therapy (mTORi) compared with patients with late induction of mTORi-based therapy.', 'Between 2003 and 2008, therapy was changed to an mTORi-based regimen in 57 patients. Patients were divided into 4 groups: group 1, early conversion (≤3 months after orthotopic liver transplantation) to mTORi therapy, and with impaired perioperative renal function; group 2, early conversion to mTORi therapy, and with normal perioperative renal function; group 3, late conversion to mTORi therapy, and with impaired perioperative renal function; and group 4, late conversion to mTORi therapy, and with normal perioperative renal function.', 'One month after conversion, the mean (SD) increase in calculated glomerular filtration rate in groups 1 (early conversion) and 3 (late conversion) was comparable: 8 (9) mL/min vs 7 (10) mL/min. At month 3, the increase in calculated glomerular filtration rate between groups 1 and 3 was significant (15 [11] mL/min vs 9 [15] mL/min; P = .04), an effect that persisted at month 6 (16 [12] mL/min vs 10 [12] mL/min; P = .05) and month 12 (22 [14] mL/min vs 12 [15] mL/min; P = .04).'] Is timing of conversion to mammalian target of rapamycin inhibitors crucial in liver transplant recipients with impaired renal function at transplantation?