The clinical course of acute pancreatitis varies from a mild, transitory illness to a severe, rapidly fatal disease. In about 80% to 90% of cases pancreatitis presents as a mild, self-limiting disease with low morbidity and mortality. Unlike mild pancreatitis, necrotizing pancreatitis develops in about 15% of patients, with infection of pancreatic and peripancreatic necrosis representing the single most important risk factor for a fatal outcome. Infection of pancreatic necrosis in the natural course develops in the second and third week after onset of the disease and is reported in 40% to 70% of patients with necrotizing pancreatitis. Just recently, prevention of infection by prophylactic antibiotic treatment and assessment of the infection status of pancreatic necrosis by fine-needle aspiration have been established in the management of severe pancreatitis. Because medical treatment alone will result in a mortality rate of almost 100% in patients with signs of local and systemic septic complications, patients with infected necrosis must undergo surgical intervention, which consists of an organ-preserving necrosectomy combined with a postoperative closed lavage concept that maximizes further evacuation of infected debris and exudate. However, intensive care treatment, including prophylactic antibiotics, reduces the infection rate and delays the need for surgery in most patients until the third or fourth week after the onset of symptoms. At that time, debridement of necrosis is technically easier to perform, due to better demarcation between viable and necrotic tissue compared with necrosectomy earlier in the disease. In contrast, surgery is rarely needed in the presence of sterile pancreatic necrosis. In those patients the conservative approach is supported by the present data.