Objectives: After organ transplant, strategies to simplify the therapeutic regimen may improve adherence and prevent rejection and/or graft loss. The aim of the present study was to evaluate the safety of conversion from once-daily prolonged-release tacrolimus (Advagraf; Astellas Pharma Europe Limited, Middlesex, UK) to once-daily extended-release tacrolimus (Envarsus; Chiesi SAS, Nanterre, France) in stable adult liver transplant recipients. Materials and Methods: This observational study included 44 liver transplant patients (median age of 59 y; 63.6% men; median delay after transplant of 72.5 mo). Conversion was based on a 1:0.70 proportion. Results: Mean dose of tacrolimus was 2.65 ± 1.24 mg/day before conversion and 2.09 ± 1.68 mg/day after conversion (P < .05), with ratio of 1:0.79. Mean serum tacrolimus trough level increased after conversion (4.92 ± 1.65 vs 5.60 ± 2.89 ng/mL; P < .05), with ratio of 1:1.14. Six months after conversion, mean dose of tacrolimus was 1.65 ± 0.93 mg/day (ratio of 1:0.62) and mean serum tacrolimus trough level was 4.82 ± 1.85 ng/mL, similar to the initial level before conversion. At the end of follow-up, 2 patients had returned to once-daily prolonged-release tacrolimus because of adverse effects (allergy, digestive trouble), which resolved thereafter. The mean cost of tacrolimus therapy was 5.54 ± 2.29 Euros/patient/day before conversion and 4.11 ± 2.32 Euros/patient/day after conversion (P < .05). Conclusions:Conversion from prolonged-release to extended-release tacrolimus in stable liver transplant patients is safe and cost-effective; however, initially, dose adaptations and careful monitoring are required.