This is a prospective randomized controlled study to evaluate feasibility and safety of early steroid withdrawal after 6mg/kg vs 4.5mg/kg Thymoglobulin induction therapy in kidney transplantation. Patients are enrolled from June, 2015 for 24 months. They are randomized to either 6mg/kg or 4.5mg/kg Thymoglobulin induction group. Steroid withdrawal is done within one week after kidney transplantation for all the patients. Maintenance immunosuppressants are Tacrolimus and Mycophenolate mofetil (or Myfortic). Primary outcome is a composite of biopsy-proven acute rejection, delayed graft function, graft loss or death within one year post transplant.

Inclusion Criteria:

• Male or female patients with renal failure from 18 to 70 years of age
• Candidates for cadaveric or living donor kidney transplantation
• Patients who are able and willing to consent the protocol of the study

Exclusion Criteria:

• Patients who have been receiving immunosuppressive therapy before transplantation
• Patients who have received an investigational medication within the past 30 days
• Patients who have a known contraindication to the administration of antithymocyte globulin
• Patients who are suspected or known to have an infection or were seropositive for hepatitis B surface antigen (HBsAg), antibody against hepatitis B core antigen (anti-HBcAg), hepatitis C virus (HCV), or human immunodeficiency virus (HIV)
• Patients who have had cancer (except non melanoma skin cancer) within the previous 2 years
• Pregnant women, nursing mothers, and women of childbearing potential who were not using condoms or oral contraceptives