Abstract: Objective To compare and analyze the effects of body mass index (BMI) levels on graft function after kidney transplantation. Methods Clinical data about 238 renal transplant recipients admitted to our hospital from January 2008 to December 2011 were retrospectively analyzed. Recipients were divided into three groups based on BMI at the time of transplantation: group A (BMI＜ 24.9 kg/m²), group B (BMI 25-29.9 kg/m²) and group C (BMI≥30 kg/m²). The comparative analysis included onset of delayed graft function (DGF), acute rejection episodes and time of serum creatinine recovery to normal. Results DGF occurred more frequently in group C (55%) than in group A (20.93%) and group B(21.74%) (P＜ 0.01). No significant differences of acute rejection episodes were found among the three groups with 12.79% in group A, 16.30% in group B and 43.33% in group C (P=0.088). Time of serum creatinine recovery to normal was 7.65±3.23 days in group A, 6.99±5.36 days in group B and 11.45±6.20 days in group C (P＜ 0.01). Conclusion Obese recipients (BMI≥30 kg/m²) are suffered to more incidence of DGF and longer time of serum creatinine recovery to normal than non-obese recipients.