Acute pancreatitis is most frequently of biliary or alcoholic origin and less frequently due to iatrogenic (ERCP, medication) or metabolic causes. Diagnosis is usually based on abdominal pain and elevation of serum lipase to more than three-times the normal limit. Acute pancreatitis can either resolve quickly following an oedematous swelling or present as a severe necrotizing form. A major risk is the systemic inflammatory response syndrome (SIRS), which can cause multi-organ failure. Prediction of disease course is initially difficult, thus necessitating immediate therapy and regular re-evaluation. In order to prove or exclude biliary genesis, abdominal ultrasonography should first be performed and endoscopic ultrasound may also be required. Primary therapy includes rapid and correctly dosed fluid substitution. Biliary pancreatitis requires causal treatment. In the case of cholangitis, stone extraction must be performed immediately; in the absence of cholangitis, it might be advisable to wait for spontaneous stone clearance. Timely cholecystectomy is necessary in all cases of biliary pancreatitis.