Seventy nine pancreatic specimens were obtained from patients treated with pancreatic resection for acute necrotising pancreatitis. The necrotising process had started in the periphery of the gland, so that eight of seventy nine cases contained peripancreatic (mainly fat) necrosis only without any parenchymal necrosis. Peripheral parenchymal necrosis was characterised by a severe inflammatory reaction, with multinucleated leucocytes and microabscess. In the deep parts of the pancreas coagulation necrosis was found. Vascular changes (thrombosis, vessel necrosis) correlated with postoperative haemorrhagic complications, but they did not seem to have any important role in the necrotising process. The vascular changes seemed to be a secondary phenomenon. In clinical practice the most important aspects in reporting the histology of acute necrotising pancreatitis are the extent of parenchymal necrosis, because the surgeon may overestimate its extent, and the existence of vascular changes, because of the correlation with postoperative recovery.