Urinary ribonuclease output and indices of renal tubular integrity were evaluated in control subjects and patients with pancreatic cancer, chronic pancreatitis and extrapancreatic diseases. The aim of the study was to ascertain the contribution to such diagnoses of ribonuclease determination in urine, and the possible influence of tubular damage on the extent of ribonuclease excretion. Information from the ribonuclease assay in urine offered no advantage over that obtained by the same determination in serum; tubular damage may contribution in some cases to an elevated ribonuclease excretion.