Thymoglobulin, or antithymocyte globulin (ATG), and anti-interleukin 2α (IL-2α) chain receptor antibody (IL-2αRAb) achieve comparable good results in kidney transplantation notwithstanding different actions on immune cells. Previously, we reported the usefulness of flow cytometry (FC) analysis of lymphocyte subsets present in peripheral blood sample (PBL) and fine-needle aspiration biopsies (FNABs) for clinical surveillance, as, FC reaches very high predictive positive values for acute rejection diagnosis. Now we report an FC study on 2 kidney transplantation (KT) groups under ATG (n = 19) and IL-2αRAb (n = 24) treatment. Both groups were further treated with calcineurin inhibitors mycophenolate mofetil (MMF) and prednisone. PBL and FNAB samples were collected on day 7 post-KT, stained for several T- and B-lymphocyte subsets, and acquired using FACScan. Statistical analysis were done by Mann-Whitney U test. FNAB results showed a significant downregulation by ATG of CD3 (P < .001), CD4 (P = .009), CD4CD29 (P = .003), and CD2 (P ≤ .001) and significant upregulation of death receptor (DR) (P = .03), CD3CD69 (P < .001), and CD3CD25 (P < .0001) as compared to groups treated with IL-2αRAb. For PBL, the same trend was seen for CD3, CD4, CD2, CD3CD25, CD3CD69, CD4CD29, and DR plus a downregulation of CD45RO (P = .001) and an upregulation of CD4CD45RA (P < .0001) in IL-2αRAb. This study shows that among stable KTs, ATG as compared to IL-2αRAb induces a significant downregulation of a subset of T-memory (CD4CD29) cells but an upregulation of antigen-experienced cells (CD45RO). Further, ATG decreases CD2, CD3, CD4, and naïve (CD45RA) and stimulates T cells as translated by CD3CD69 and DR. As it should be expected from an IL-2αRAb agent, CD25 cells were virtually eliminated.