Patient safety is at the forefront of health care and nursing practice. Oncology nurses strive to provide safe oncologic care in their management of cancer, treatments, and side effects. Oncologic emergencies such as tumor lysis syndrome (TLS), however, are serious complications of cancer and cancer treatment. TLS often is seen in hematologic malignancies, such as lymphomas and leukemias, that frequently occur in older adults. As the population in the United States continues to age, nurses must be prepared to manage oncologic emergencies in older adults. Understanding the risk factors and preventive strategies for TLS provides oncology nurses with a foundation for managing a serious treatment complication. Patients and their caregivers need to understand the importance of preventive measures for TLS; therefore, patient education must be a critical part of the oncology nurse's plan of care.