Catalytic phospholipase A2 activity (CA-PLA2) and the concentration of immunoreactive pancreatic PLA2 (IR-PLA2) were measured in serum samples from 12 patients with multiple injuries (median Injury Severity Score: 41). CA-PLA2 was increased in all patients and positive correlations were found between the extent of the increase of CA-PLA2, mortality, and impairment of pulmonary function. IR-PLA2 values were slightly increased in the serum of nine patients with multiple injuries. Of these nine patients, eight had an additional blunt abdominal trauma. On the other hand, no relationship was found between IR-PLA2 and CA-PLA2 values. This finding was confirmed by immunoadsorption experiments with an antiserum to human pancreatic PLA2, which demonstrated that the increased serum levels of IR-PLA2 were not responsible for the increased CA-PLA2 values. The results suggest the existence of at least two immunologically different phospholipase A2 enzymes in sera of patients with multiple injuries.