Pharmacokinetic, pharmacodynamic and pharmacogenetic information can help to choose the best treatment and the best dose for each patient. The genetic polymorphism of enzymes metabolizing treatments can affect their efficacy and safety. Concerning tacrolimus, CYP3A5 activity is a major determinant of the dose needed to reach target concentrations. This study is aimed at evaluating the impact of both donor and recipient CYP3A5 genetic polymorphisms on tacrolimus exposure in patients with hepatic transplant.