The authors have retrospectively analysed the drainage fluid of 39 patients undergoing Whipple's operation over a 18-year period. The aim of the study was to assess whether the volume and amylase concentration of the drainage fluid were good criteria of healing of the pancreatico-jejunal anastomosis. The patients have been divided into two groups: Group I (30 patients) with no complications at the pancreatico-jejunostomy--Group II (9 patients) with a pancreatic leak. The analysis of the volume, amylase concentration and amylase index (Log of the amylase concentration x volume) showed that the groups had clearly different profiles: in group I all three criteria were rapidly decreasing, while they remained abnormally high in group II. Those criteria may help the clinician in the monitoring of individual patients; they also may prove useful in prospective studies evaluating new means of prevention of this anastomosis.