Introduction: Graft function early after kidney transplantation is an important parameter in determining the outcome of operation. Urinary and plasma neutrophil gelatinase-associated lipocalin (NGAL), a member of the lipocalin protein family, has been advocated as a sensitive, early biomarker for predicting early renal graft after transplantation. The functions of NGAL appears to be expressed in stress conditions and in tissues undergoing involution. It rapidly accumulates in the kidney tubules and urine after nephrotoxic and ischemic insults. Objectives: This study aimed to examine the prognostic role of NGAL early after renal transplantation. Patients and Methods: A total of 37 kidney recipients were enrolled from a teaching centre in Tabriz within a 6-month period of time. Plasma NGAL was measured immediately before and at 6 and 12 hours post-transplantation. Changes of serum creatinine were documented daily within the first week post-operation. Acute kidney injury (AKI)/graft rejection during the first week after transplantation was the outcome variable. Results: There were 22 males (59.5%) and 15 females (40.5%) with the mean age of 34.93 ± 14.97 years (range: 12-59) in the study group. AKI/graft rejection developed in 12 patients (32.4%). The mean post-transplantation plasma NGAL levels and serum creatinine at all time points were significantly higher in patients with AKI/graft rejection. The best prognostic role was found for plasma NGAL at 12 hours (sensitivity = 100%, specificity = 92%; cut-off value = 309 ng/ml), far better than the prognostic accuracy of corresponding serum creatinine (sensitivity = 66.7%, specificity = 61.9%). Conclusion: Plasma NGAL, particularly 12 hours after transplantation, is a very sensitive and specific biomarker for predicting acute renal injury.