Morphological changes of the lung occur frequently in fatal acute hemorrhagic pancreatitis. The pulmonary alterations are independent of mechanical ventilation and therefore not due to iatrogenic damage caused by high inspired oxygen concentrations. The histological findings are similar to those seen in the so-called shock lung syndrome. The pulmonary lesion develops progressively and three stages can be separated: early, late, and final phase. The pulmonary complications in acute hemorrhagic pancreatitis may be explained by the release of mediators such as pancreatic enzymes or free fatty acids into the blood stream. In acute hemorrhagic pancreatitis a close monitoring for shock parameters is necessary. A fall in arterial PO2 is an early indication for mechanical ventilation, including positive end-expiratory pressure.