Inclusion Criteria:

1. Written informed consent with the date of the patient must be obtained
2. Patient is the recipient of a liver transplant from 6 to 24 months prior to enrollment
3. Patient is currently receiving Prograf or Prograf + MMF based immunosuppressive therapy
4. At screening the liver and kidney function of patient is stable (defined as Serum creatinine is normal and ALT or AST is <= 2 times the upper value of normal range)
5. Patient has the stable whole blood trough level concentration of Prograf (defined as tacrolimus trough concentrations of 2-10ng/ml measured 14 days prior to enrollment), and is clinically stable in the opinion of the investigator

Exclusion Criteria:

1. Patient has received an organ transplant other than a kidney
2. Patient has experienced any rejection episode within 90 days prior to enrollment in the study, any rejection episode within the last 6 months that required anti-lymphocyte antibody therapy
3. Patient is currently receiving other immunosuppressant therapy, eg. sirolimus
4. Patient with liver recurrent cancer, or metastasis, or other cancer
5. Patient has any unstable medical condition that could interfere with the study objectives
6. Patient is currently participating in another clinical trial and/or is taking or has been taking an investigational drug in the 30 days prior to enrollment
7. Patient is allergic macrolide antibiotics or tacrolimus
8. Patient has psychiatric disorder, in the opinion of the investigator, may invalidate communication with the investigator
9. Patient is currently receiving any medications, which is know to alter the CYP450 3A enzyme system (including grapefruit juice)