Upregulation of hypoxia-inducible factor-1alpha (HIF-1alpha) in response to ischemic states has been suggested to have a role in the development of chronic allograft nephropathy. Deposition of C4d in the peritubular capillaries of renal allografts has been reported to be a sensitive marker of acute humoral rejection. The purpose of this study was to determine the effects of HIF-1alpha expression and C4d deposition in implantation biopsies of renal allografts. Implantation biopsies and 22 rejection proved biopsies were performed in 54 renal transplant recipients between December 1996 and July 1999. The mean follow-up was 82.8 months. Immunohistochemical studies were performed using a mouse monoclonal antibody for HIF-1alpha expression and a rabbit polyclonal antibody for C4d detection. HIF-1alpha was demonstrated in 19 of 54 implantation biopsies (35%), and C4d deposition in one (1.9%). The HIF-1alpha-positive group included a higher percentage of deceased donor organs (66.4% vs 17.1%; P = .002) and longer mean cold ischemia times (261.3 +/- 231 vs 103 +/- 40 min; P = .008) compared with the HIF-1alpha-negative group. The relative risks (95% confidence intervals) of expression of HIF-1alpha for allograft rejection, chronic allograft nephropathy, and graft loss were 1.53 (0.82-2.87), 0.61 (0.06-5.50), and 2.45 (0.62-9.85). The C4d-positive patient developed acute accelerated rejection on postoperative day 4. In the present study, the expression of HIF-1alpha showed a significant correlation with the use of a deceased donor kidney and with cold ischemia time. However, there were no significant effects on the prognosis for a graft after implantation of a kidney with HIF-1alpha expression.