Hyperamylasaemia may occur following abdominal aortic aneurysm rupture and its use as a prognostic indicator has been suggested. However, the isoenzyme responsible for the rise in serum amylase has not been investigated. In this study, isoenzyme analysis was performed on the serum of patients noted to have a raised amylase from their routine biochemistry samples. Individual cases were then reviewed regarding clinical course and outcome. The pancreas has been thought to be the predominant source of the observed hyperamylasaemia. However, in this study a mixed picture of pancreatic and salivary isoenzymes was found. Of the four highest recorded amylase levels two were salivary in origin, one pancreatic and one mixed. The highest recorded amylase level was of salivary origin in a patient that survived without any major complication. The four patients that died all showed evidence of gut infarction/ischaemia. Two had hyperamylasaemia of a mixed pattern, one pancreatic and one of salivary origin.