In acute pancreatitis, infection of pancreatic or peripancreatic necrosis is the most important risk factor determining the patient’s outcome. Pancreatic necrosis develops within the first 4 days after the onset of the disease. Infection occurs in 40-70% of patients with necrotizing pancreatitis. The incidence of pancreatic infection is 24, 36 and 71% in the first, second and third weeks, respectively. Infection of pancreatic or peripancreatic necrosis can be detected quickly and reliably by ultrasound- or by computed-tomography-guided fine-needle puncture, followed by gram staining and/or culture. Only patients with necrotizing pancreatitis and proven infection should be managed surgically, whereas patients without infection should be managed conservatively. Conservative treatment has to be carried out in an intensive-care unit, and consists of symptomatic therapy to stabilize the cardiocirculatory, pulmonary and renal functions, and the treatment of pain. If infection of pancreatic or peripancreatic necrosis occurs, the patient must be operated on. In such patients, the University Hospital of Bern performs necrosectomy and postoperative closed lav age of the lesser sac.