This study was performed to investigate the behavior of phospholipase A2 (PLA2) in serum and urine of patients with chronic pancreatic diseases and to ascertain whether any factors influenced the results. In 30 controls, 45 patients with pancreatic cancer, 54 with chronic pancreatitis, and 64 with extrapancreatic diseases, serum and urinary PLA2, pancreatic isoamylase and RNase, and urinary N-acetylglucosaminidase (NAG) were measured. Serum PLA2 levels were higher in patients with chronic pancreatitis than in all the other groups. In our patients, only occasionally was urinary PLA2 elevated, the increase occurring almost exclusively in the presence of an acute inflammatory disease, e.g., relapsed chronic pancreatitis or active inflammatory bowel disease. A correlation was found between serum PLA2 and serum RNase, an indicator of tissue damage, but not between serum PLA2 and pancreatic isoamylase. Urinary PLA2 output was correlated with its renal input and with RNase output. No correlation was found between PLA2 output and pancreatic isoamylase or NAG urinary excretion. In conclusion, (1) the determination of serum PLA2 activity may be an aspecific test of pancreatic disease; (2) PLA2 urinary excretion occasionally increases, especially in the presence of severe phlogosis, which occurs in chronic pancreatitis, in particular during relapse; and (3) irrespective of the tissue origin of urinary PLA2, its increased excretion may be accounted for in part by its increased circulating levels. It is, however, more likely the consequence of a renal tubular dysfunction, which is sometimes found in patients with pancreatic diseases.