Recent studies provide conflicting conclusions regarding the impact of delayed graft function (DGF) on the long-term outcome of renal transplantation. Some centres report DGF as an independent risk factor for reduced long-term graft and patient survival, while others report no impact on long-term outcome. Further scrutiny of data from these studies reveals differences in the definition of DGF, definition of long-term outcome, and statistical methods that may partly explain the variability. The commonest definition of DGF is the need for dialysis in the first week post-transplant, but this may be less informative than definitions that consider DGF as a continuous variable such as time to achieving creatinine clearance > 10ml/min. Acute rejection (AR) occurs more commonly in patients with DGF and variability in the impact of DGF may also relate to strategies to detect and treat AR during DGF. Centres with a vigilant strategy are likely to note a lower impact of DGF because the associated long-term adverse impact of AR is minimised. Furthermore, many centres reduce the dose of calcineurin inhibiting drugs and/or use polyclonal antibody therapy during DGF but the long-term impact of this strategy is unclear. Newer agents such as humanised anti-IL2 monoclonal antibodies and rapamycin may have a role, but controlled studies are required to define the optimal immunosuppressive regimen for patients with DGF. In the meantime, measures to minimise ischaemic damage to the transplant kidney and intensive surveillance for AR with weekly renal biopsy in patients with DGF are recommended.