Currently, there is no specific therapy for acute pancreatitis. The management of the disease is supportive in approximately 80% of patients who suffer mild to moderate attacks. The remaining 20% of patients develop one or more major complications and require intensive care. Classification of acute pancreatitis according to severity is, therefore, necessary for proper management. Severe acute pancreatitis is detected early by the determination of circulating levels of polymorphonuclear elastase (PMN-E) and/or C-reactive protein (CRP). Patients with low levels of both PMN-E and CRP who have no major local or systemic complication of the disease can be classified as having mild acute pancreatitis. These patients require only supportive therapy and basic monitoring of vital functions. Patients with high levels of PMN-E and/or CRP and disease-related complications should be classified as severe. These patients should be managed in an intensive care unit for close monitoring of cardiovascular, respiratory, renal, metabolic, and hematological functions, and for early treatment of complications. Any organic dysfunction needs to be specifically treated. Development of extrapancreatic organ failure is closely related to the extent of pancreatic necrosis. Therefore, contrast-enhanced computed tomography (CT) should be performed in every patient classified as having severe acute pancreatitis. If sepsis develops, fine-needle ultrasound or CT-guided aspiration of necrotic tissue for bacteriological examination should be performed. Infected necrosis and persistent systemic failure under maximal intensive treatment require surgical treatment by necrosectomy and continuous lavage of the lesser sac. Late local complications of acute pancreatitis (i.e., abscesses and persistent pseudocyst) must be drained percutaneously or, more often, surgically.