A multicenter, randomized, double-blind trial was carried out to evaluate the efficacy of gabexate mesylate (FOY) in acute pancreatitis. One hundred unselected patients were randomly allocated into two groups: 51 were assigned to receive FOY (12 mg/kg/day as continuous intravenous infusion for a minimum of 4 days and a maximum of 12 days), and 49 were allocated to placebo. The groups were comparable in demographic, clinical and biochemical parameters, etiology of pancreatitis, and disease severity, which was gererally mild. Gallstones were the main etiological factor. All patients received fluid and electrolyte replacement, analgesia and nasogastric suction for at least 48 h after admission. Experimental therapy was initiated no later than 12 h after the beginning of symptoms. The results showed no statistically significant differences between the two groups with respect to the evolution of clinical and biochemical parameters, analgesic requirements, development of complications, hospitalization time or mortality at completion of the trial. In conclusion, early treatment with FOY does not appear to have any demonstrable beneficial effects in acute pancreatitis.