The optimal dose of Thymoglobulin as an induction regimen in Asian living donor kidney recipients has been rarely reported. Patients were randomly assigned to receive either 4.5 mg/kg (ATG4.5 group, n=19) or 6.0 mg/kg (ATG6.0 group, n=17) Thymoglobulin. All patients had corticosteroid withdrawal within 7 days. The primary end point was a composite of biopsy-proven acute rejection, de novo donor specific antibody, or graft failure. Until 49 months post-transplant, the rate of the composite end point was 47.4% in the ATG4.5 group whereas 17.6% in the ATG6.0 group. There was one case of death-censored graft failure in the ATG4.5 group whereas there was no mortality during the follow-up period (22 to 49 months). This study was ceased earlier than expected because we concerned about the more increasing risk of the composite end point in the ATG4.5 group. Compared to pre-transplantation, T (CD3+CD56-) cells, NK (CD3-CD56+) cells, and NKT (CD3+CD56+) cells were significantly decreased whereas B (CD19+) cells were not significantly affected by Thymoglobulin in the first week. Although T and NKT cells had recovered to the pre-transplant value in both groups, NK cells in the ATG6.0 were kept suppressed while NK cells in the ATG4.5 group had recovered to the pre-transplant value. Interestingly, CD56dimCD57+ cells were significantly increased whereas CD56dimNKG2A+ cells was significantly decreased in the ATG4.5 group compared with the ATG6.0 group until six months post-transplant. ATG 4.5 mg/kg induction and early corticosteroid withdrawal tended to increase the rate of de novo donor-specific antibody and biopsy-proven acute rejection. (ClinicalTrials.gov: NCT02447822)