Current standard prophylactic immunosuppression in renal transplantation includes tacrolimus, a calcineurin inhibitor, dosed twice daily. In Canada, oral tacrolimus has been available as a twice daily formulation marketed as Prograf® since 1997. It has recently become available in an extended release formulation called Advagraf®, which is dosed once daily. Advagraf® has been demonstrated to be therapeutically equivalent to Prograf® in the renal transplant maintenance population, and as a result it has been is approved as an alternative to the twice daily formulation in these patients. There is an evolving and expanding positive clinical experience with Advagraf® in kidney transplantation and it has shown to be preferred by many patients, due to the diminished dosing frequency. In clinical trials, Advagraf® has been shown to have other potential benefits over Prograf® such as less inter and intra-patient variability, improved cardiovascular profiles, and improved kidney function. Compared to Prograf®, Advagraf® also has a lower Cmin or 'trough' concentration as well as a lower Cmax or 'peak' concentration. The purpose of this study is to convert stabilized renal transplant patients currently receiving Prograf® to Advagraf®, to investigate these potential therapeutic benefits.