Body Mass Index (BMI) is one of the most accurate means of determining healthy body weight. In recent years, the prevalence of obesity has increased in both the general, and thus, the transplant population. The correlation between BMI and renal transplant outcome has remained controversial. In this study we aimed 1) To determine correlation between BMI and outcome of renal transplantation and 2) To evaluate prevalence of obesity in our transplant patients. From Jan. 1996 to Dec. 2002, we performed 1718 kidney transplants. BMI was documented for 1433 pts. There were 3 groups based on: normal weight Group I (n = 877) BMI 1-25; overweight Group II (n = 406) BMI 26-30; and obese Group III (n = 150) BMI > 30. There were no statistically significant differences between 3 Groups in live vs. cadaveric donor, immunosuppressive therapy (FK vs. Cyclosporine), waiting time, CIT, or mismatch however, obesity is more dominant in males (p< 0.01), and in Hispanics and Caucasians (p< 0.01). Incidence of obesity in our patients was 8.7% in 1996 vs. 22.0% in 2002. Group I did not have a statistically better graft or patient outcome than Group II, however, Group I had significantly better graft outcome (p = 0.04) than Group III (obese), with 89% & 67% at 1 & 5 yrs for Group I vs. 86% 55% at 1 & 5 yrs for Group III respectively (p=0.04). Moreover, patient survival was also significantly better in Group I than Group III (p = 0.03) at 95% & 93% at 1 & 5 yrs for Group 1 vs. 92% & 82% at 1 & 5 yrs. for Group III respectively. This study shows a definite correlation between BMI and outcome of renal transplantation. Normal weight patients had on average a 12% better cadaveric graft patient survival than obese pts over 5 yrs. Moreover, the incidence of obesity increased approximately 2% per year.