The advent of computed tomographic scan with its wide use in the evaluation of acute pancreatitis has opened up a new topic in pancreatology i.e. fluid collections. Fluid collections in and around the pancreas occur often in acute pancreatitis and were defined by the Atlanta Symposium on Acute Pancreatitis in 1992. Two decades since the Atlanta Conference additional experience has brought to light the inadequacy and poor understanding of the terms used by different specialists involved in the care of patients with acute pancreatitis when interpreting imaging modalities and the need for a uniformly used classification system. The deficiencies of the Atlanta definitions and advances in medicine have led to a proposed revision of the Atlanta classification promulgated by the Acute Pancreatitis Classification Working Group. The newly used terms "acute peripancreatic fluid collections," "pancreatic pseudocyst," "postnecrotic pancreatic/peripancreatic fluid collections," and "walled-off pancreatic necrosis" are to be clearly understood in the interpretation of imaging studies. The current treatment methods for fluid collections are diverse and depend on accurate interpretations of radiologic tests. Management options include conservative treatment, percutaneous catheter drainage, open and laparoscopic surgery, and endoscopic drainage. The choice of treatment depends on a correct diagnosis of the type of fluid collection. In this study we have attempted to clarify the management and clinical features of different types of fluid collections as they have been initially defined under the 1992 Atlanta Classification and revised by the Working Group's proposed categorization.