Abstract. Simultaneous pancreas-kidney transplant (SPK) is now a common treatment for insulin-dependent diabetic patients with end-stage renal disease. Renal graft survival rates after SPK have been less well studied. This study compared the kidney survival results for 3642 SPK and 2374 cadaveric renal transplants (CRT) in type I diabetic patients at 112 US transplant centers reported to UNOS during 1994 through 1997. The analysis included follow-up information through September 2000. The kidney graft survival rates were significantly lower among recipients of CRT compared with SPK recipients (P Ͻ 0.001). Patients who received SPK were younger, less often sensitized, transplanted after shorter periods on dialysis, and less often black. The donors of SPK organs were younger, more often died from head trauma, were less often female, and more often black. SPK renal grafts were transplanted with a shorter cold ischemia time to more poorly HLA-matched recipients. After adjustment of these and other factors, whether a patient was recipient of CRT or SPK was not associated with increased risk of kidney graft failure or patient death. SPK recipients experienced half the rate of delayed kidney function (11% versus 23%) but nearly double the rate of rejections during the initial hospitalization (15% versus 9%) compared with CRT recipients. SPK was associated with better renal allograft survival compared with CRT, despite a higher rate of renal allograft rejection. This observation was explained by favorable donor and recipient factors in the SPK group. After controlling for these factors, SPK provided no protective or detrimental effect on short-term renal allograft or patient survival. bunnapradist@cshs.org