Pancreatitis may be acute or chronic, mild or severe. Acute necrotizing pancreatitis remains the most serious form of acute pancreatitis, and accounts for the majority of complications. Although there is an established nomenclature for acute pancreatitis and resultant pancreatic fluid collections, we have identified a group of patients who represent a separate entity and whose collections may prompt additional change in the nomenclature of acute pancreatitis. These patients have radiographically well-defined subacute collections which evolve from severe acute necrotizing pancreatitis involving greater than 30% of the gland. Since these collections are not completely liquefied, they do not meet criteria for pseudocysts, but at the same time, they are also morphologically distinct from acute pancreatic necrosis seen during initial presentation of acute pancreatitis. We have termed these subacute collections 'organized pancreatic necrosis'. This article summarizes necrotizing pancreatitis and its complications, focuses on treatment of the complex pancreatic and peripancreatic collections found in these patients, and emphasizes endoscopic management of organized pancreatic necrosis.