Delayed return to kidney function after transplantation is characterized essentially by acute ischemic tubular necrosis. It remains frequent and has no curative treatment. However, an induction treatment of antilymphocyte serum may reduce the delay in recuperation. In patients with delayed function, the maintenance immunosuppressive treatment should take into account the excessive risk of acute rejection over the short term and the more rapid deterioration of renal function over the long term. This means that biopsies to screen for acute rejection should be done systematically before the end of the 3rd month and anticalcineurin toxicity-sparing treatment should be considered, replacing anticalcineurins immediately with belatacept or after the 3-month acute period with proliferation signal inhibitors, if the kidney histology tests permit. In all cases, the classical measures of kidney protection remain indispensable.