Circulatory dearrangement during acute pancreatitis has been studied with the aid of differently sized (15 and 50 µm) and labelled microspheres, intracardially infused before and 7 h after induction of experimental pancreatitis. A drop of arterial pressure (–26%), cardiac output (–65%) and left ventricular work (–87%) was registered together with a rise of resistance in systemic (+87%) and pulmonary (+188%) vessels. The fractions of cardiac output were increased to the heart (+64%), brain (+51%), liver (+194%), stomach (+112%), small intestine (+49%) and pancreas (+37%). Systemic arteriovenous shunting of small compared to large microspheres to the lung was markedly reduced and there was no shunting through the preportal area. The circulatory dearrangement was similar to that of a 30% acute blood volume withdrawal, and might be explained by the extensive plasma loss (–45%).