Body mass index (BMI) is strongly associated with outcome of renal transplantation independent of other risk factors. The aim of this study was to evaluate the impact of low BMI on the graft survival in renal transplant recipients. We included 115 (M/F: 80/35) (age: 34.56±11.14 years, post-transplantation follow-up duration: 5 years) renal transplant recipients in our study. The demographic, laboratory data, presence of acute and chronic rejection were obtained from hospital records retrospectively. The pre and posttransplantation 1st years’ BMIs were calculated and patients were grouped into two with respect to their post-transplantation BMIs: Group I: BMI<19 kg/m2 (17,8±1,0) (n=23) and Group II: BMI>=19 kg/m2 (23,7±1,8) (n=92). Twenty (87,0%) of 23 patients had low pre-transplantation BMI (p<0.0001). Age at transplantation, pre-transplantation dialysis duration and acute rejection episodes were similar in both groups. Although serum creatinine level at time of discharge after transplantation was lower in low-BMI group (p<0.03), yearly detected levels were significantly higher than normal-BMI group (p=0.01). Follow-up serum albumin, triglyceride and cholesterol levels were lower in Group I. According to the five year data, presence of chronic rejection and graft loss were more frequent in low-BMI group (73.9% and 20.7%, p<0.001 and 73.9% and 31.5%, p<0.001, respectively). In conclusion, low BMI is an adverse prognostic factor after transplantation. In order to improve graft outcome, pre-transplantation evaluation of recipients’ metabolic status and early intensive dietary advice and follow-up for normalization of BMI is recommended.