Tumor lysis syndrome(TLS)is a serious complication of anti-cancer chemotherapy due to the spontaneous or therapyrelated rapid lysis of malignant cells. TLS is characterized by hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia, which result in acute renal failure and metabolic acidosis. Factors predisposing to the development of TLS include a higher growth rate of cancerous cells, a higher sensitivity to chemotherapy, impaired renal function before chemotherapy, elevated lactate dehydrogenase and uric acid serum levels, and a large tumor burden such as huge mass formation and extensive bone marrow involvement. Patients with TLS should be treated carefully with proper fluid management, urinary alkalization, correction of acidosis and electrolyte unbalance, inhibition of the formation of uric acid or destruction of the already circulating uric acid molecules, and a reduction of chemotherapy intensity. Furthermore, the recombinant urate oxidase(rasburicase)significantly reduces the morbidity and mortality of TLS. Patients with malignant tumors must be treated with the knowledge that the proper management prior to chemotherapy, an early diagnosis, and an early aggressive treatment can prevent the occurrence of TLS.