Electrolyte disturbances are frequently encountered in critically ill oncology patients. Hyponatremia and hypernatremia as well as hypocalcemia and hypercalcemia are among the most commonly encountered electrolyte abnormalities. In the intensive care unit, management of critical electrolyte disturbances is focused on initial evaluation and immediate treatment plan to prevent severe complications. A PubMed search was performed to identify best available evidence for evaluation and management of dysnatremias, hypocalcemia, and hypercalcemia. Current literature was reviewed regarding the management of electrolyte disturbances. The role of new therapeutic options, for example, vaptans for hyponatremia, teriparatide for hypocalcemia, and denosumab for hypercalcemia, is discussed. Early diagnosis and appropriate management are expected to reduce adverse outcomes.