The accumulation of 99Tcm-citrate in abscesses and arthritic joints has previously been demonstrated. In the present study its usefulness was evaluated in 10 mongrel cats with acute pancreatitis induced by metronidazole infusion. Five cats, used as normal controls, were given physiological saline. All 15 cats were injected intravenously with 185 MBq 99Tcm-citrate. Scintigrams were obtained at 30 min intervals up to 2 h after injection by a gamma camera. The cats were then sacrificed. Tissue samples were obtained, weighed and counted against a 1/1000 dilution of the injected dose. In normal cats the kidneys and the urinary bladder were the only organs that could be visualized. In acute pancreatitis the pancreas and its exudate in the abdomen were also evident on the images. The pancreas to other neighbouring organ ratios increased 2.3-9.7 fold in acute pancreatitis compared to normal controls. Gross autoradiograms showed localization of radioactivity in the lobules of pancreas. Histologic examination of sections of pancreas demonstrated oedema, haemorrhage and some fat necrosis in pancreatic parenchyma, confirming acute pancreatitis. In conclusion, it has been demonstrated that acute pancreatitis in cats can be visualized scintigraphically with 99Tcm-citrate.