Summary The aim of this study was to determine the efficacy, safety, and immunosuppressant adherence in 125 stable liver transplant (LT) patients converted from twice‐daily tacrolimus (TAC BID) to once‐daily TAC (TAC OD). Tacrolimus trough levels, laboratory parameters, metabolic disorders, selected patient reported outcomes, and adverse events were assessed. Mean TAC trough level concentration was 6.1 ± 2.3 ng/ml at study entry, decreased to 5.5 ± 2.1 ng/ml (P = 0.016) and 5.5 ± 2.2 ng/ml (P = 0.019) after 1 and 2 weeks, respectively, and tended to equal the baseline value during further follow‐up. At week 1, TAC concentrations were lower in 62.4% of patients and higher in 36.0% when compared with baseline. Renal and cardiovascular risk factors remained stable and no rejection episodes occurred over 12 months. Adverse events were consistent with the safety profile known from previous studies with TAC BID. Nonadherence measured by the “Basel Assessment of Adherence Scale to Immunosuppressives” was evident in 66.4% at study entry and decreased to 30.9% postconversion (P < 0.0001). Prevalence of nonadherence at baseline was significantly higher in patients converted >2 years after LT and in those ≤60 years of age. Conversion to TAC OD is safe, enhances immunosuppressant adherence and should be accompanied by a close TAC level monitoring during the initial period.