PURPOSE: We designed this study to identify the risk factors affecting the quality of graft after live donor kidney transplantation. METHODS: The study cohort included 259 adult patients who had been followed up for an average of 37 months after transplantation. Cyclosporine (CsA) and steroids were used as main immunosuppressive agents. Seven variables [HLA match, numbers of acute rejection (AR) within post-transplant 1 year, blood type compatibility, use of anti-lymphocyte antibody, age of donor (DA), age of recipient, and the donor kidney weight to recipient body weight ratio (KW/BW)] were examined by multiple regression analysis during the first 3 years. Serum creatinine (Scr), creatinine clearance rate (Ccr) and the 24 hours urinary excretion of protein (24 UP) were used as parameters. RESULTS: AR, DA, or KW/BW independently affected the quality of graft function. Scr, Ccr, or 24 UP at post-transplant 1 year was strongly correlated with AR (p<0.0001, p=0.002, or p=0.002, respectively). However, Scr, Ccr, or 24 UP at post-transplant 3 years was strongly affected by KW/BW (p<0.0001, p<0.0001, or p=0.008, respectively) or DA (p<0.0001, p=0.001, or p=0.039, respectively). CONCLUSION: Non-immunologic factors independently affected the graft function through the study periods. The impact of non-immunologic factors on the function of the graft increased year by year. During renal allocation, KW/BW and DA should be included as reference indices to improve the long-term graft function.