Bacterial infection of pancreatic necrotic tissue is a frequent complication of severe acute pancreatitis. Infected pancreatic necrotic tissue is observed in 30-70% of all patients suffering from necrotizing pancreatitis. It is the leading cause of deaths in severe acute pancreatitis, with mortality rates ranging from 15 to 30%. The incidence of infection increases with the extent of the necrotic areas and with the time after onset of pancreatitis. Compared to patients with sterile necrosis, those with infection of the necrotic areas have an increased mortality, and systemic complications occur more frequently. Standard treatment for infected pancreatic necrotic tissue is surgical debridement, whereas conservative management is feasible in approximately 30% of the patients with sterile necrosis. As bacterial infection of pancreatic necrotic tissue has a tremendous impact on the prognosis of the disease and on the patient's clinical course, efforts have been made to prevent it. Although clinical and experimental data provide evidence that prophylactic antibiotics have beneficial effects on the outcome and course of patients with severe acute pancreatitis, this topic has to be investigated further. General recommendations concerning the early use of antibiotics have to await the results of larger, double-blind studies.