Acute pancreatitis is characterized by clinical, morphological, and functional aspects. Severe abdominal pain with progression during the first hours after onset is the leading symptom. In the majority of patients acute pancreatitis had a "mild" clinical course, but 10 to 20% will develop severe local and systemic complications. Symptoms at the onset of disease are not specific and need consideration of several other diagnoses. Elevation of pancreatic serum enzymes is the main parameter in the diagnosis of acute pancreatitis. Besides the traditional parameter of total amylase, several specific pancreatic enzymes (e.g. pancreatic amylase, lipase, immunoreactive trypsin or elastase) are now widely used in clinical routine and guarantee a higher diagnostic specificity. The imaging procedures ultrasonography and computed tomography aid in identifying etiological factors in grading the severity of the disease and deciding therapeutic strategies. Endoscopic retrograde chol- angiopancreatography is most sensitive in detecting biliary lithiasis and can be successfully complemented by sphincterotomy if needed. Besides complex clinical and laboratory criteria, several biochemical markers (e.g. C-reactive protein, PMN-elastase, trypsinogen activation peptides) have been found to be valid for the detection of pancreatic necrosis and are of definite prognostic value. On the basis of such detailed information, the therapeutic strategy can be planned in a straight-forward manner.