At our center, since 1982, a body mass index (BMI) of less than 30 has been a prerequisite for placing a patient on the waiting list for renal transplantation. This decision was made because obese transplant recipients seemed to have a less than favorable post-transplant outcome. The aim of this study was to evaluate whether this requirement is still justified. Forty-six patients with a BMI above 30 underwent primary cadaveric renal transplantation between 1972 and 1993. For each of these obese patients, five consecutive non-obese (BMI 20-25) control patients were selected. Patient and graft survival, causes of graft loss, and acute rejection rate were evaluated for the two patient groups before and after the year 1982. Within the first 30 post-transplant days, one patient (2%) and 11 grafts (24%) were lost in the group of obese patients whereas seven patients (3%) and 36 grafts (16%) were lost in the control group. Among the obese patients, renal circulatory complications were a major cause of graft loss. In the period 1973-1981, the 1-year patient survival rate was 65% among obese patients versus 75% among controls from 1982 to 1993, this was 90% versus 93%. From 1973 to 1981, the 1-year graft survival rate was 25% among obese patients versus 53% among controls (P < 0.05); from 1982 to 1993, it was 68% versus 84% (P = NS). Multivariate analysis showed that the immunosuppressive regimen, age of the patient, BMI, and cold ischemia time of the graft had a significant influence on graft survival. The acute rejection rate within the first 30 days was 28% among obese patients and 35% among controls (P = NS). We conclude that a BMI below or equal to 30 is still justified as a prerequisite for placement on the waiting list for renal transplantation, for despite an overall improvement, the outcome of renal transplantation in obese patients remains worse than that in non-obese patients.