Steroid Withdrawal Immunosuppression After Renal Transplantation

Inclusion Criteria: * Patients aged more than 13 years who received a primary kidney transplant * Subject who is using CNI ± purine synthesis inhibitor + steroid without change within the past 3 months (except the dosage) * serum creatinine \< 2 mg/dL and the variation of serum creatinine \< 30% during the past 3 months * Proteinuria ≤ 1g quantified by 24 hour urine or spot urine protein/creatinine ratio \< 1.0 * Subjects who agree with written informed consent Exclusion Criteria: * Subjects who received combined non-renal transplantation. * Subject who received re-transplantation * Deceased donor without a heartbeat * Patients with hypersensitivity to Mycophenolate sodium, Mycophenolate acid or Mycophenolate Mofetil or to any of the excipients. * Patient with HGPRT(Hypoxanthin e-guanine phosphoribosyl-transferase) such as Lesch-Nyhan syndrome and kelley-Seegmiller syndrome. * HLA-identical living related donor * ABO blood group incompatible * HIV, HBsAg, or HCV Ab tests (+) * Abnormal liver function test (AST or ALT or total bilirubin\> upper normal limit x3) ANC \< 1,500/μL or WBC \< 2,500/μL or platelet \< 750,000/μL * Women who are either pregnant, lactating, planning to become pregnant in the next 12 months. * Subjects with history of cancer, except successfully treated, localized nonmelanocytic skin cancer Subjects with clinically significant infections within the past 3 months.