Abnormal renal function markedly influences the clinical management of cancer patients. While the neoplasm may cause renal damage in itself, the damage may be exacerbated by treatment with chemotherapeutic agents. Since many chemotherapeutic agents are metabolized and excreted through the kidneys, their use may represent a major risk factor for the development of renal abnormalities. Moreover, when renal failure is present before chemotherapy treatment, certain drugs need dose adjustments or are not indicated. Careful monitoring of renal function during chemotherapy is thus necessary and preventive measures should be adopted when possible to reduce the occurrence of renal dysfunction.