A living related kidney transplant recipient, who showed very characterstic findings in immunologic study, was reported. This patient was a retransplant recipient. First graft of this patient was his mother's kidney, and the second graft was his older sister's kidney. HLA compatibility between the patient and the second donor was one haplotype identical. Although the patient was responsive in mixed-leukocyte-culture (MLC) against the second donor before first transplantation, MLC and cell-mediated-lympholysis (CML) tests before retransplantation showed specific unresponsiveness to the second donor. During 36 months after retransplantation, no rejection episodes nor any complications have been observed.