Optima: Optimizing Prograf Therapy in Maintenance Allografts II

Inclusion Criteria: * Patient is the recipient of a cadervic or living donor renal transplant. * Patient was 18 years of age at time of transplant. * Patient is at least 6 months post-transplant. * Patient has been on a cyclosporine-based immunosuppressive regimen since the transplant. * Patient has a functioning allograft and a Cockcroft/Gault estimate of creatinine clearance \>or= 35 mL/min within four weeks prior to randomization. * Patient or legal guardian has signed and dated an Institutional Review Board (IRB) approved informed consent document and is willing and able to follow study procedures. * Females are not pregnant and agree to practice effective birth control while receiving immunosuppressant medication. Exclusion Criteria: * Patient is the recipient of a solid organ transplant other than the kidney. * Patient experienced biopsy-confirmed, acute rejection, (Banff 97 criteria)within 3 months before randomization that required treatment, which is defined as antilymphocyte therapy, corticosteroids, or an increase in the number or dose of immunosuppressant medication. * Patient has recurrence of primary renal disease, or de novo renal disease. * Patient has a urine protein of \> 1.5g/24 hours or two successive urinalyses sent to and reported by the laboratory indicating albuminuria greater than 2+ within 6 months prior to enrollment. * Patient has an estimated creatinine clearance \< 35 mL/min calculated using Cockcroft/Gault formula within four weeks prior to randomization. * Patient has changed adjunctive immunosuppressant therapy within one month if randomization. * Patient is pregnant or lactating. * Patient is a known carrier of any of the HIV viruses. * Patient has a known or suspected malignancy (except for treated squamous or basal cell skin cancers) \< 5 years before randomization or a history of post-transplant lymphoproliferative disease (PTLD). * Patient has a known hypersensitivity to tacrolimus, or any of the excipients of the drug.