Secondary pancreatic infections are most serious and life threatening complications of acute necrotizing pancreatitis. The risk of secondary infection is to a large extend related to duration and extension of pancreatic or peripancreatic necrosis. The combination of abdominal CT-scan with guided percutaneous needle aspiration has been demonstrated to be highly reliable on differentiating between sterile and infected pancreatic necrosis. Previous results suggest a major role of enteric pathogens in this disease. Due to the type of microorganisms and the defence capacity of the patient, the pancreatic infection might result in either elimination of the microorganism, unlimited propagation within devitalized tissue (infected necrosis) or they may remain localized (abscess formation). Though the most fulminant course of acute pancreatitis is found in patients with early infected necrosis. In these cases an operation is usually necessary within 14 days after onset of symptoms. Persistence or new development of typical symptoms two to five weeks after initial improvement should raise the suspicion of abscess. The finding of infection is an absolute indication for surgical intervention. The intention of surgical treatment in combination with antibiotic therapy is to remove devitalized pancreatic and peripancreatic tissue, evacuate all purulent material and provide continuous drainage either by lavage or "open" abdominal treatment. In this article basic procedures of diagnosis and therapy are discussed.