The addition of daclizumab (a human immunoglobulin G1 monoclonal antibody that blocks interleukin-2 receptors on T lymphocytes) to mycophenolate mofetil (MMF) and steroids is a new option for initial immunosuppression in patients undergoing liver transplantation (LT) with impaired renal function. We evaluated the efficacy and safety of daclizumab in preventing rejection in 25 patients with impaired kidney function undergoing LT. Patients with serum creatinine (Cr) levels greater than 2 mg/dL immediately before LT were administered initial immunosuppression with daclizumab, 1 mg/kg, in addition to MMF, 2 g/d, and methylprednisolone. Tacrolimus was added after kidney function improved (when Cr levels improved by >25% of initial value). Daclizumab-treated patients were compared retrospectively with 2 other groups of patients who underwent LT with kidney impairment (Cr > 2 mg/dL): 56 patients were administered OKT3 induction, and 48 patients were administered lowdose tacrolimus. The incidence of rejection and infection (bacterial, fungal, and viral), need for preoperative and postoperative dialysis, Cr level immediately post-LT and at 3 months, and graft and patient survival were analyzed. There was no difference among the groups in 3-month Cr levels or the incidence of rejection or fungal or viral infection. The daclizumab group had fewer bacterial infections (n ؍ 13) than the tacrolimus group (n ؍ 28) and significantly fewer than the OKT3 group (n ؍ 58; P ؍ .006). Only 1 patient (4%) in the daclizumab group required dialysis post-LT versus 13 patients in each of the other groups (OKT3, 23.21%; P < .05; tacrolimus, 27%). In the daclizumab group, 2-year patient and graft survival rates were statistically significant compared with the lowdose tacrolimus group (89% and 81% v 73% and 69%, respectively; P ؍ .06). There were no side effects related to daclizumab use, and all patients tolerated the drug well. In patients with impaired renal function before LT, daclizumab-based initial immunosuppression can be used safely to reduce the risk for infection and need for dialysis post-LT, with improved long-term graft and patient survival. (Liver Transpl 2001;7:220-225.)T here is no agreement on initial immunosuppressive regimens in patients undergoing liver transplantation (LT) with impaired renal function. [1][2][3] Suggested regimens include OKT3 induction in combination with azathioprine and steroids, with or without low doses of calcineurin inhibitors. [4][5][6] A new option in this circumstance is the use of daclizumab with mycophenolate mofetil (MMF) and steroids. Daclizumab is a human immunoglobulin G1 monoclonal antibody that blocks the ␣ chain of interleukin-2 receptors on activated T lymphocytes. [7][8][9] Previous studies have shown the efficacy of daclizumab in preventing rejection in kidney transplantation and LT without immediate side effects. [7][8][9][10][11] In particular, daclizumab does not cause cytokine release syndrome, neurotoxicity, or nephrotoxicity, which makes it an appealing alternative t...