Acute renal failure (AKI) is a high-prevalence complication in patients with cancer. The risk of AKI after cancer diagnosis is 18% in the first year, 27% in the fifth year, and 40% of critically ill patients with cancer require renal replacement therapy. The causes of AKI may be pre-renal due to hemodynamic problems, related to the cancer, metabolic complications, and drug or surgical treatment. One must preventively protect renal function by hydration, use of non-nephrotoxic drugs, correction of anemia, prevention of contrast agent-induced AKI (CI-AKI), and adjustment of cancer therapy in patients with CKD. It is essential to check basal renal function, creatinine trend, electrolytes, urinalysis and proteinuria, perform imaging, renal biopsy if necessary. The evaluation of patients should be multidisciplinary and timely including the initiation of renal replacement treatment (RRT). There are different modalities of replacement treatment depending on the clinical picture of the patient with AKI and cancer: intermittent hemodialysis (IHD), intermittent prolonged replacement therapy (PIRRT), and continuous replacement therapy (CRRT). The concept of dose administered, as opposed to prescribed dose, as well as the anticoagulation of extracorporeal circuits, which must be regional with citrate (RCA) as the first choice in the management of CRRT, turns out to be fundamental in order to achieve optimal circuit anticoagulation, with reduction of coagulation episodes and downtime, while maintaining the patient’s coagulation status. The onco-nephrologic multidisciplinary approach is crucial to reduce the mortality rate, which is still high in this category of patients.Copyright by Società Italiana di Nefrologia SIN, Rome, Italy.