This topic highlights the results of the literature review on calcium therapy during cardiac arrest and cardiopulmonary resuscitation according to the Patient/population, Intervention, Comparator, Outcome structure. Eligible studies were assigned to one of the five levels of evidence. Their quality was rated as either good, fair, or poor and then classified as supportive, neutral, or opposing according to the outcome benefits. Among the 48 articles retrieved, 10 articles fulfilled all the criteria for analysis for the Guidelines preparation. There is no evidence that the administration of calcium during cardiopulmonary resuscitation improves survival from cardiac arrest irrespective of the presenting rhythm. In the setting of hyperkalemia, calcium channel blocker intoxication, hypocalcemia, and hypermagnesemia, the role of calcium remains unclear because of the limited amount of evidence. The main limitation is the scarcity of data, most of which relate to anoxic cardiac arrest, accounting for no more than 25% of the causes of cardiac arrest in humans.