Introduction. Monitoring of graft function by creatinine concentrations in serum and calculated glomerular filtration rate (GFR) is recommended after kidney transplantation. KDIGO recommendations on the treatment of transplant patients advocate usage of one of the existing mathematical equations based on serum creatinine. We compared clinical application of three equations based on serum creatinine in monitoring the function of transplanted kidney. Methods. A total number of 55 adult patients who received their first renal allograft from living donors at our transplant center in between 2011-2014 were included into the study. Renal allograft GFR was estimated by the Cockroft-Gault, Nankivell and MDRD formula, and correlated with clinical parameters of donors and recipients. Results. The mean age of recipients was 35.7±9.5 (range 16-58), and the mean age of donors was 55.5±9.0 (34- 77) years. Out of this group of 55 transplant patients, 50(90.91%) were on hemodialysis (HD) prior to transplantation. HD treatment was shorter than 24 months in 37(74%) transplant patients. The calculated GFR with MDRD equation showed the highest mean value at 6 and 12 months (68.46±21.5; 68.39±24.6, respectively) and the lowest at 48 months (42.79±12.9). According to the Cockroft&Gault equation GFR was the highest at 12 months (88.91±24.9) and the lowest at 48 months (66.53±18.1 ml/min). The highest mean level (80.53±17.7) of the calculated GFR with the Nankivell equation was obtained at 12 months and the lowest (67.81±16.7 ml/min) at 48 months. The values of Pearson’s correlation coefficient between the calculated GFR and the MDRD at 2 years after transplantation according to donor’s age of r=-0.3224, correlation between GFR and the Cockfroft & Gault at 6 and 12 months and donor’s age (r=-0.2735 and r=-0.2818), and correlation between GFR and the Nankivell at 2 years and donor’s age of r=-0.2681, suggested a conclusion that calculated GFR was lower in recipients who had an older donors. Conclusion. Our analysis showed difference in the calculated GFR with different equations at the same time points. Using one mathematical equation during the total post-transplantation period would be a recommended method in order to eliminate the discrepancy in determining the stage of kidney failure.