A case of severe hypoglycemia (30 mg/dL) after resection of unilateral pheochromocytoma is reported. Consciousness regained after 20 gm dextrose water was given intravenously. Rebound insulin storm is highly suspected as the main mechanism for the development of post-operative hypoglycemia. Administration of alpha and beta adrenergic blockers may also contribute to the severity of the hypoglycemia. Closely monitoring blood sugar level during the perioperative period is the only way to prevent the occurrence of such a catastrophe.