A retrospective study was made of 75 consecutive patients treated for a tumour of the head of the pancreas and the peri-ampullary region from January 1978 to August 1981. These patients underwent either pancreatic resection--pancreatoduodenectomy (n = 24) and total pancreatectomy (n = 10)--palliative procedures (n = 29) or exploratory laparotomy (n = 12). Clinical signs and diagnostic procedures, such as ultrasonography and coeliac arteriography, were studied for their value in preoperative assessment of operability. Vaso-invasion, as revealed by arteriography and, to a lesser extent, ultrasonographic signs of a tumour and the absence of jaundice were poor prognostic signs. The operative mortality was 8 per cent for the group as a whole, but somewhat higher (13 per cent) for the group that underwent pancreatoduodenectomy. No patient died after total pancreatectomy. The operative mortality was 27 per cent in all patients aged 70 years or older, but only 3 per cent in patients under 70 years. One-year patient survival was 94 per cent after pancreatoduodenectomy for peri-ampullary cancer and 57 per cent after resection for cancer of the head of the pancreas. The results of this study point to pancreatic resection as the treatment of choice for resectable tumours of the peri-ampullary region and the head of the pancreas in patients under 70 years of age. Coeliac arteriography and ultrasonography have been found to be useful for preoperative classification of tumour stage.