This paper has outlined the varied renal and metabolic abnormalities which may occur as complications of antineoplastic chemotherapy. Rapid tumor lysis leading to acute uric acid nephropathy, hyperkalemia and hyperphosphatemia may complicate the treatment of patients with chemotherapy-responsive tumors. Aggressive management with intravenous hydration, urinary alkalinization and administration of allopurinol can ameliorate these complications of therapy. Many commonly used antineoplastic agents, particularly cisplatin, methotrexate, streptozotocin, and nitrosoureas, are nephrotoxic. Careful monitoring of renal function and serum electrolytes are essential during administration of these agents. In addition, intravascular volume depletion, urinary tract infection, and obstructive uropathy must always be considered when renal function deteriorates in patients with cancer. With foresight and aggressive management, many of these derangements can be ameliorated or avoided entirely and the toxicity of effective cancer chemotherapy can be minimized. Patients with established renal failure who require chemotherapy pose a particularly difficult clinical problem. Though a complete discussion of this subject is beyond the scope of this paper, Table 3 is included to provide some guidelines for dose modification in patients with altered renal function.