To evaluate the utility of fibrinogen as a prognostic factor in acute pancreatitis (PA) it was measured within 48 hours of admission in 55 patients with acute pancreatitis studied prospectively. We found that patients with fibrinogen levels above 850 mg/dl. presented a serious evolution in 55.55% of cases as compared to 10.87% of those who had levels below this figure (p less than 0.01). We conclude that fibrinogen measurement can be useful in the early evaluation of the prognosis of acute pancreatitis.