The pulmonary microvasculature was examined in two experimental models of acute pancreatitis by scanning electron microscopy of microvascular corrosion casts. Haemorrhagic pancreatitis was induced in eight male Sprague-Dawley rats using an intraductal injection of 5 per cent sodium taurocholate. Oedematous pancreatitis was induced in seven male Sprague-Dawley rats using an intravenous infusion of supramaximal doses of caerulein (5 micrograms/kg per hour). The pulmonary vessels were cast using a polymer resin and the cast studied by scanning electron microscopy at 3 and 12 h in those with haemorrhagic and at 1 and 4 h in those with oedematous pancreatitis. Vascular abnormalities were present in both models at the initial study time with abruptly terminating vessels being more prominent in the caerulein model. At the later times, however, the abnormalities in the sodium taurocholate model were much more severe, with a substantial loss of vascular density, tortuosity and abrupt terminations of those vessels present. Microvascular abnormalities may be responsible for some of the pulmonary changes seen in oedematous and haemorrhagic pancreatitis.