To evaluate the organ specificity of pancreatic phospholipase A2 (PLA2) and the diagnostic value of the elevation of serum PLA2 levels in patients with serious diseases not involving the pancreas, we studied the organ distribution of PLA2 in autopsy specimens and serum level of PLA2 in patients who required admission to an intensive care unit (ICU). PLA2 was measured by a specific radioimmunoassay (RIA), using monoclonal antibody against human pancreatic PLA2. Organ distribution of PLA2 revealed that the pancreas showed a much higher content of pancreatic PLA2 immunoreactivity than any other organ. An abnormally high value of serum PLA2 was observed in 18 of 30 patients (60%) at ICU. Both serum PLA2 and pancreatic isoamylase were elevated in 11 patients (37%). Of 11 patients with hyperphospholipasemia and hyperamylasemia, serum creatinine was elevated in five patients and blood urea nitrogen in nine patients. Serum PLA2 levels did not always rise comparably to serum creatinine and blood urea nitrogen levels. Serum PLA2 values showed the best correlation with serum lactate dehydrogenase levels among routine blood-chemistry tests. The elevation of serum PLA2 was ascribable to renal dysfunction or ischemic pancreatic damage secondary to circulatory collapse with multiple organ failure.