The severity of acute pancreatitis is correlated to the amount of necroses--pancreatic parenchymal necroses and fatty tissue necroses in the retroperitoneal spaces--the liberation of vasoactive and toxic substances and the bacterial contamination of necroses. The necrotizing pancreatits occurs in around 15 to 25% of all patients with acute pancreatitis; a local infection has been observed in around 40% of patients with necrotizing pancreatitis. Surgical treatment in patients with necrotizing pancreatitis is indicated, if they develop a surgically acute abdomen, a sepsis syndrome or a multisystem's organ failure syndrome despite ICU-treatment over at least 3 days. Bacterial contamination, proved by an ultrasound guided FNP of the necrosis is a strong indicator for surgical management. Careful necrosectomy and a continuous local lavage of the lesser sac and the necrotic cavities are most effective. Conservation of vital pancreatic tissue is a major goal of surgical treatment. The continuous local postoperative closed lavage results in a continuous evacuation of vasoactive and toxic substances, bacteria, local active enzymes and debrid tissue. Among patients with sterile pancreatic necroses only those with major necroses of more than 50% of the pancreas are candidates for surgical treatment. Hospital mortality after necrosectomy and local lavage figures in major leading series between 8 and 20%. Failure of surgical treatment of necrotizing pancreatitis is mostly due to continuing local and systemic sepsis.