Summary Plasma clearance of 51Cr‐EDTA (51Cr‐EDTA‐Cl) is an alternative method to evaluate glomerular filtration rate (GFR). This study aimed to investigate the concordance between 51Cr‐EDTA‐Cl and renal inulin clearance (In‐Cl) in renal transplant recipients as well to determine the repeatability of 51Cr‐EDTA‐Cl in kidney donors. Forty four kidney recipients and 22 kidney donors were enrolled. Simultaneous measurements of 51Cr‐EDTA‐Cl and In‐Cl were performed. A single dose of 3.7MBq of 51Cr‐EDTA was injected and the plasma disappearance curve was created by taking blood samples at 2, 4, 6 and 8 h after injection. Bland and Altman statistical approach was used to quantify the agreement between In‐Cl and 51Cr‐EDTA‐Cl and to determine the better concordance between all possibilities of measure for the 51Cr‐EDTA‐Cl. The mean of In‐Cl was 44.5 ± 17.9 ml/min/1.73 m2. There was a positive correlation between In‐Cl and all possible measurements of 51Cr‐EDTA‐Cl. 51Cr‐EDTA‐Cl with two samples taken at 4 and 8 h or at 4 and 6 h presenting the narrow limits of agreement and a difference (bias) of 2.8 and 2.7 ml/min, respectively. Two plasma sampling for 51Cr‐EDTA‐Cl was a reliable method to measure GFR compared with In‐Cl and comprises a suitable method to be used in kidney transplanted patients.