New immunosuppressive agents and regimens should be evaluated specifically in living donor liver transplant patients due to potential clinical and pharmacokinetic differences between deceased donor and living donor transplant recipients. The analysis presented here is the first direct comparison of clinical outcomes using cyclosporine microemulsion (CsA-ME) with monitoring of blood concentration at 2 hours postdose (C2) and tacrolimus-based immunosuppression in living donor liver transplantation. The analysis was conducted on the data provided by the 39 recipients of a living donor transplant out of the 495 patients enrolled in a 6-month, randomized, prospective, multicenter, open-label study (LIS2T). Patients were randomized to CsA-ME (C2 monitoring) or tacrolimus (monitoring of predose trough drug blood level [C0)]) and were administered corticosteroids with or without azathioprine. Twenty-three living-donor patients received CsA-ME and 16 received tacrolimus. By month 6, 9% of patients receiving CsA-ME and 19% of those receiving tacrolimus had lost their graft or died (not significant [NS]). Nine episodes of biopsy-proven acute rejection were reported: 4 in the CsA-ME group (17%) and 5 in the tacrolimus cohort (31%, NS). There were no significant differences in any safety parameter between groups. The most frequently reported serious adverse events were infections, which occurred in 14 patients in the CsA-ME group (61%) and 13 patients in the tacrolimus arm (81%, NS). Twelve patients in the CsA-ME arm (52%) and 5 in the tacrolimus arm (31%, NS) discontinued the study prematurely. In conclusion, CsA-ME C2 monitoring or tacrolimus both offer effective protection against rejection in living donor liver transplants while maintaining a good safety profile.