Obesity is associated with adverse cardiovascular (CV) parameters and may be involved in the pathogenesis of allograft dysfunction in renal transplant recipients (RTR). We sought the spectrum of body mass index (BMI) and the relationships between BMI, CV parameters and allograft function in prevalent RTR. Data were collected at baseline and 2 years on 90 RTR (mean age 51 years, 53% male, median transplant duration 7 years), categorized by BMI (normal, BMI < or = 24.9 kg/m2; pre-obese, BMI 25-29.9 kg/m2; obese, BMI > or = 30 kg/m2). Proteinuria and glomerular filtration rate (eGFR(MDRD)) were determined. Nine percent RTR were obese pre-transplantation compared to 30% at baseline (p < 0.001) and follow-up (25 +/- 2 months). As BMI increased, prevalence of metabolic syndrome and central obesity increased (12 vs 48 vs 85%, p < 0.001 and 3 vs 42 vs 96%, p < 0.001, respectively). Systolic blood pressure, fasting blood glucose and lipid parameters changed significantly with BMI category and over time. Proteinuria progression occurred in 65% obese RTR (23 (13-59 g/mol creatinine) to 59 (25-120 g/mol creatinine)). BMI was independently associated with proteinuria progression (beta 0.01, p = 0.008) but not with changing eGFR(MDRD.) In conclusion, obesity is common in RTR and is associated with worsening CV parameters and proteinuria progression.