Delayed graft function (DGF) and acute rejection have both been associated with reduced renal allograft survival. In some studies, they have been shown to have an interactive effect. We studied the risk factors for DGF and the relative impact of DGF and rejection on both short- and long-term survival in recipients of cadaveric renal transplants. Data from the Oxford Transplant Centre Database were assessed on 710 cadaver allografts over a 10-yr period, during which time all recipients received cyclosporin-based immunosuppressive protocols. The interaction between DGF and acute rejection was examined using logistic and Cox multivariate regression. Long cold ischaemia time (CIT), sensitisation and older donor age were found to be independent predictors of DGF. The occurrence of DGF resulted in a reduced 5-yr survival (56 vs. 75%). However, the effect of DGF was confined to the first year post-transplant, as there was no significant difference in survival, as measured by half-life (t1/2) of grafts functioning at 1 yr, with DGF alone and a group with good early function (t1/2 = 21.3 vs. 20.0 yr). There was no increase in acute rejection in grafts with DGF. However, the combination of DGF and acute rejection resulted in the worst short-term graft survival (68% at 1 yr, compared to 92.3% in those grafts with no DGF or acute rejection) and this continued over the long term (t1/2 = 10.5 yr). These data suggest that early function is critical to the success of renal transplantation. The effects of DGF are limited to the first year post-transplant. Long-term graft survival may be improved by efforts to limit CITs, particularly for grafts from older donors and sensitised recipients.