Leptin is a small peptide hormone that is mainly produced in adipose tissues. Leptin plays animportant role in regulating appetite and energy expenditure and may be involved in modulatingbone mineralization. This study was designed to test the association of serum leptin kidneyfunction in renal transplant recipients. We studied 72 kidney transplanted recipients. In thisstudy a significant difference of serum leptin between males and females with higher values infemales was seen (p>0.05). There was not relationship between serum leptin with body massindex, age and creatinine clearance (p>0.05). A negative relationship between serum leptin andthe duration of kidney transplantation was found (r= -0.26, p= 0.03). The clinical significanceof inverse association between serum leptin and the duration of renal transplantation, shouldconsider more in larger studies.