BACKGROUND/AIMS: Continuous intravenous glucagon is frequently used in the management of severe congenital hyperinsulinism (HI), but its efficacy in these patients has not been systematically evaluated. The aim of this study was to describe the use of continuous intravenous glucagon and to evaluate its effect on the glucose infusion rate (GIR) requirement in infants with HI. METHODS: Retrospective chart review of children with HI who received continuous intravenous glucagon for prevention of hypoglycemia at the Children's Hospital of Philadelphia between 2003 and 2013. RESULTS: Forty (22 male) infants were included, and median (IQR) age at glucagon treatment was 29 (23, 54) days. Median glucagon dose was 205 (178, 235) mcg/kg/day and duration of treatment was 5 (3, 9) days. GIR reduced from 18.5 (12.9, 22.8) to 11 (6.6, 17.5) mg/kg/min 24 h after starting glucagon (p < 0.001), and hypoglycemia frequency reduced from 1.9 (1.3, 2.9) to 0.7 (0.3, 1.2) episodes per day. Vomiting (n = 11, 13%), rash (n = 2, 2%), and respiratory distress (n = 15, 19%) were seen during glucagon treatment. CONCLUSION: An intravenous glucagon infusion reduces the required GIR to maintain euglycemia, decreasing the risks associated with the administration of high fluid volume or fluids with high-glucose concentrations.