Some 20% of cases of acute pancreatitis are associated with pancreatic and/or peripancreatic necrosis. Mortality of necrotizing pancreatitis is higher than that of acute interstitial pancreatitis, especially if there is secondary pancreatic infection. Despite the fact that patients with infected necrosis are in general more seriously ill than those with sterile necrosis, it is not possible at present by any individual laboratory test or constellation of tests to determine precisely which patients are infected or will develop pancreatic infection. CT-guided percutaneous aspiration with bacteriological sampling continues to be a very safe, reliable method of distinguishing severe sterile pancreatitis from pancreatic infection. Improved survival for infected necrosis depends on earlier recognition and prompt effective surgical debridement. Necrosectomy and post-operative local lavage appear to improve survival in infected necrosis.