Since its introduction in renal transplantation in 1999, sirolimus is being used by an increasing number of liver transplant centers. Compared to the calcineurin inhibitors, sirolimus acts through a separate signal transduction pathway and has a myriad of important biologic effects including: inhibition of lymphocyte proliferation, inhibition of fibrosis and fibroblast proliferation, and antineoplastic effects. The clinical side-effect profile of this drug is also different than calcineurin inhibitors. Most important, sirolimus does not cause glucose intolerance, hypertension, or renal insufficiency. As a result, this drug offers significant potential advantages over conventional immunosuppressive agents. However, sirolimus may cause hyperlipidemia and has also been associated with hepatic artery thrombosis in liver transplant recipients. This review will summarize the published data on sirolimus in liver transplantation, focusing on the potential advantages and disadvantage of the use of this drug in liver transplant recipients. Finally, the potential benefits of antifibrosis and antineoplastic effects of sirolimus in liver transplant recipients will be discussed.