In this article, we review the prevalence of magnesium (Mg) deficiency in patients undergoing platinum-based chemotherapy (PBC), summarize research on IV and oral Mg in supportive care, discuss the role of Mg in carcinogenesis, explore different forms of oral Mg, investigate current best evidence on the effect of Mg on survivorship, and review ways for clinicians to identify and remedy early signs of Mg depletion. Methods.PubMed, Natural Medicines Comprehensive Database, Natural Standard Database, Google Scholar, and the book Herb, Nutrient, and Drug Interactions were used to locate relevant studies with publication dates up to May 15, 2015.Results. Hypomagnesemia is known to occur in 29% to 100% of patients undergoing PBC. While serum Mg does not appear to be a reliable indicator of Mg deficiency, there are a wide variety of clinical signs and symptoms that can be used for screening. These include loss of appetite, nausea, vomiting, headache, weakness, numbness, tingling, muscle cramps, constipation, fatigue, anxiety, restless legs, insomnia, depression, irritability, asthma, refractory hypocalcemia and hypokalemia, high blood pressure, tremor, tetany, prolonged QT interval, cardiac arrhythmias, ataxia, carpopedal spasms, seizures, metabolic alkylosis, psychiatric disturbances, and cortical blindness. Prophylactic IV Mg in pre- and posthydration followed by oral Mg supplementation can play an important role in preventing platinum (Pt)-induced serum hypomagnesemia. Mg supplementation with PBC is safe because it does not appear to affect progression-free survival, overall survival, antitumor activity, or blood concentrations of chemotherapy. Conclusions. Prophylactic IV Mg followed by oral Mg can prevent Pt-induced hypomagnesemia and alleviate Mg deficiency symptoms in cancer patients.