The proportion of expanded criteria donor (ECD) kidneys transplanted in North America is steadily increasing. By definition, graft survival is shorter for ECD than standard criteria donor (SCD) kidneys. Seeking to identify factors associated with low posttransplant glomerular filtration rates (GFR), we retrospectively reviewed data on 390 consecutive patients transplanted in our center from January 1999 to December 2006 including 78% SCD and 22% ECD by UNOS criteria. We analyzed donor and patient characteristics, HLA mismatches, cold ischemia time (CIT) and delayed graft function (DGF). Pulsatile perfusion was not used. The average CIT was 14.6 hours for all SCD and ECD cases. All patients received thymoglobulin, a calcineurin inhibitor, mycophenolate mofetil, and steroids. The only factor associated with low estimated GFR in the entire ECD cohort was CIT. The average CIT for the ECD group was 18.3 hours, whereas it was only 13.6 hours for those in the SCD group (P < .001). We observed that at 6 months posttransplant, those in the ECD group are 2.2 times more likely (odds ratio, 2.23; 95% confidence interval, 1.065-4.654; P = .033) to have an estimated GFR < or =50 mL/min/1.73 m(2) compared with those in the SCD group for CIT up to 18 hours. The higher odds ratio for low estimated GFR was sustained at 3 years posttransplant. In our center, a lengthy CIT was an early risk factor associated with impaired renal function. We concluded that all efforts should be made to reduce CIT.