Tumor lysis syndrome (TLS) is an oncologic emergency resulting from rapid cancer cell destruction as a result of spontaneous tumor necrosis or treatment-related cell lysis. Concomitant metabolic abnormalities characterizing this syndrome include hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia and acute renal failure, which make this syndrome a life-threatening condition. Therefore, awareness and aggressive management to prevent TLS is recommended in high-risk cancer patients. This article updates the pathogenesis, diagnostic criteria, risk factors, prevention, and treatment of TLS.