The nephrotoxic potential of ifosfamide is now clearly recognized but the true incidence is unknown and risk factors are uncertain. There are, as yet, few studies which systemically explore these issues although many centers have collected data from patients receiving ifosfamide. These support the need for collaborative studies to look at the influence of probable risk factors such as age, cumulative/dose, schedule, and exposure to other nephrotoxic drugs. The ability to detect acute subclinical changes in renal function may provide the opportunity to predict subsequent clinical toxicity. The consensus of opinion recorded so far provides the basis of recommendations for future studies.