Acute oedematous pancreatitis was induced in Wistar male rats by intravenous (i.v.) infusion of cerulein at the rate of 5.10(-6)g.kg-1.h-1 for 3 or 6 hrs. The effects of dimethylsulfoxide (DMSO)-hydroxyl radical scavenger in this model of disease were examined. DMSO was injected i.v., 0.75 g.kg-1, at 0 and 3 hrs during cerulein infusion. Treatment with this agent exerted a protective effect on the rat pancreas in the cerulein-induced acute pancreatitis. This effect is expressed by inhibition of lipid peroxidation in pancreatic tissue, less oedema formation, diminution of hyperlipasemia and a significant reduction in acinar cell vacuolisation. Our data suggest that besides the hydroxyl radical, other oxidants (secondary?) may cause cytotoxicity in this model of disease. We suggest that phagocytic inflammatory cells provide such oxidants.