The basic principles of the initial management of acute pancreatitis are adequate monitoring of vital signs, fluid replacement, correction of any electrolyte imbalance, nutritional support, and the prevention of local and systemic complications. Patients with severe acute pancreatitis should be transferred to a medical facility where adequate monitoring and intensive medical care are available. Strict cardiovascular and respiratory monitoring is mandatory for maintaining the cardiopulmonary system in patients with severe acute pancreatitis. Maximum fluid replacement is needed to stabilize the cardiovascular system. Prophylactic antibiotic administration is recommended to prevent infectious complications in patients with necrotizing pancreatitis. Although the efficacy of the intravenous administration of protease inhibitors is still a matter of controversy, there is a consensus in Japan that a large dose of a synthetic protease inhibitor should be given to patients with severe acute pancreatitis in order to prevent organ failure and other complications. Enteral feeding is superior to parenteral nutrition when it comes to the nutritional support of patients with severe acute pancreatitis. The JPN Guidelines recommend, as optional measures, blood purification therapy and continuous regional arterial infusion of a protease inhibitor and antibiotics, depending on the patient's condition.