Copeptin is the carboxyl-terminal part of the vasopressin precursor protein, which is an independent predictor of the onset of chronic kidney disease and the rapid reduction of glomerular filtration rate. We conducted a study to determine the clinical significance of copeptin as an early predictor of renal graft dysfunction in renal transplant recipients. In the living or deceased donor kidney transplant recipient, serum creatinine and copeptin concentrations are checked for operation day, post-operation day 1, 3, and 7 and post-operation month 1 and 12. Acute rejection is defined as a case in which a sudden decrease in renal function is accompanied by a histological change after renal transplantation. Eight patients who underwent living or deceased donor kidney transplantation were enrolled in the study from July 2018 to December 2019. Seven patients received a deceased donor kidney transplant and one had a living donor kidney transplant. There were five male and three female with an average age of 50.6 ± 5.9 years. Four patients underwent histological examination and transplantation rejection was confirmed. All were acute T-cell rejection. No statistically significant correlation was found between creatinine level and copeptin concentration. (P = 0.935) There was no significant correlation between preoperative copeptin levels and rejection. (p = 0.686) Copeptin has been identified in previous cohort studies as an independent predictor of the onset of new chronic kidney disease and a decrease in glomerular filtration rate. Glomerular filtration rate is generally regarded as the best indicator of transplant kidney function and as a predictor of graft and patient survival. Copeptin was expected to be used to identify individuals with a high risk of declining graft function or with a high likelihood of rejection, but did not show statistically significant results. More patients may be needed for further study.