Tumor lysis syndrome (TLS) is a clinical condition that is caused by a massive lysis of tumor cells that accumulate very rapidly and disturb hemodynamics. This oncologic emergency requires immediate intervention. Tumor lysis syndrome was first described in the 19th century. Since then, it has become a well-known disease with improved management measures. Tumor lysis syndrome can occur after any type of neoplasm. It is highly associated with rapidly proliferating tumors compared with those that are well demarcated, such as acute lymphoblastic leukemia and high-grade non-Hodgkin lymphoma. Initiation of chemotherapy, radiotherapy, or steroid treatment may trigger TLS, or it may develop spontaneously. The release of massive quantities of intracellular contents may produce hyperkalemia, hyperphosphatemia, secondary hypocalcemia, hyperuricemia, and acute renal failure. Prevention and treatment measures include intravenous hydration, use of allopurinol and rasburicase, management of TLS-associated electrolyte abnormalities, and renal replacement therapy; the use of urine alkalinization remains controversial. In this article, we summarize the findings of case series and case reports published over the past 6 years in an effort to help familiarize clinicians better recognize and manage TLS.