This study was undertaken in order to ascertain the behaviour of amylase and trypsin fractional clearances in chronic pancreatic disease and to speculate on the factors involved. Renal tubular function was also assessed in these patients. An increase of both clearances was found in a number of patients with pancreatic cancer and chronic pancreatitis. Amylase urinary output seems to be mainly related to the circulating enzyme levels; urinary IRT is principally accounted for by a functional tubular impairment. Tubular damage was observed in a number of patients with chronic pancreatic disease. This was related to pancreatic inflammation in chronic pancreatitis and to several factors, among which jaundice and pancreatic damage, in pancreatic cancer.