Background. A significant role in solving the problem of renal replacement therapy should be played by kidney transplantation, which is now widely regarded as the optimal method for treating end-stage renal failure. An important problem remains the survival of the graft, and therefore it is necessary to find the most optimal method for diagnosing the earliest lesion of the graft.Objective. Examine the possibility of using glomerular filtration rate calculated by the Cockcroft–Gault (C&G) and EPI formulas to assess renal allograft function.Design and methods. 216 patients with functioning renal allograft were examined, among them 92 women and 124 men, the average age was 56.8 ± 12.8 years. All patients completed: determination of serum creatinine level (Cr) (mmol/l), determination of the level of daily proteinuria (g/day), calculation of glomerular filtration rate using the formula EPI (ml/min) and Cockcroft–Gault formula (ml/min). All patients received immunosuppressive therapy.Results. We divided patients into 4 groups: 1 — patients without daily proteinuria with serum creatinine (Cr) < 0.110 mmol/l, 2 — patients without daily proteinuria with Cr > 0.110 mmol/l, 3 — patients with daily proteinuria less than 0.15 g/day with Cr < 0.110 mmol/l, 4 — patients with daily proteinuria more than 0.15 g/day with Cr > 0.110 mmol/l. The average Cr level was in the group 1 — 0.093 ± 0.001 mmol/l, in 2 — 0.162 ± 0.005 mmol/l, and 0.081 ± 0.002 mmol/l, and 0.135 ± 0.012 mmol/l in 3 and 4 groups, respectively. Glomerular filtration rate Cockcroft–Gault and EPI, respectively, in group 1 — 82.1 ± 4.4 ml/min and 74.9 ± 3.7 ml/min, in 2 — 55.3 ± 2.9 ml/min and 46.8 ± 2.4 ml/min, at 3 — 79.4 ± 2.8 ml/min and 71.1 ± 2.5 ml/min, at 4 — 51.2 ± 1.6 ml/min and 42.5 ± 1.2 ml/min. Сr level is not a sufficiently accurate indicator of allograft dysfunction, as in group 1 it was significantly higher than in group 3 (p < 0.01), exactly the same picture was observed when comparing groups 2 and 4. At the same time, glomerular filtration rate using the Cockcroft–Gault formula and EPI formula was slightly higher in group 3 and 4 compared with group 1 and 2.Conclusion. Calculating glomerular filtration rate using the Cockcroft–Gault formula and EPI formula is a more sensitive method for assessing renal allograft dysfunction.