We have evaluated the changes in plasma total and ionic calcium levels in twenty hepatic transplantations in pediatric patients. Direct intraoperative monitoring of ionic calcium is fundamental, because its variability is unrelated with total calcium levels; in addition, normal ionic calcium levels contribute to the hemodynamic stability of the patient. Although at the end of the operation total and ionic calcium levels were similar to the postinduction measurement, their values were dissociated in the perianhepatic period. In the anhepatic phase ionic calcium reached its lowest value (1.00 mmol/l) although total calcium increased above postinduction level from 2.13 to 2.46 mmol/l (p less than 0.05). In hepatic transplantation in pediatric patients calcium administration is indicated during the transfusion of citrated blood, being particularly necessary during the anhepatic phase to prevent ionic hypocalcemia.