Obesity, which has become an increasing problem worldwide, poses a risk for kidney transplant recipients both before and after surgery. In this literature review, we studied the effects of obesity before and after kidney transplant. There are numerous studies and different opinions on the effects of obesity on graft function before and after transplant. Obesity prolongs surgery time and the ischemic process. A large cohort study of 11 836 recipients noted a close association between body mass index and delayed renal transplant and delayed graft function. However, another study found that being overweight or obese before transplant did not have any effects over the medium and long term. A 20-year follow-up study indicated that the firstyear body mass index in recipients after renal transplant had a greater effect on graft function and survival than body mass index before transplant. Still, another study found that body mass index had no effects on graft function and survival. In the study, 3-year graft function and mortality rates of morbidly obese people without diabetes, the functional status without dialysis, and living-donor transplant were reported to be much lower than in those with normal weight. In conclusion, there is no consensus on the effects of obesity before and after transplant, and it has been pointed out that more research should be done on this subject.