The value of serum C-reactive protein, lactate dehydrogenase isoenzymes and erythrocyte sedimentation rate in predicting the outcome of acute pancreatitis was evaluated for 57 episodes in 54 patients. Serum C-reactive protein levels on day 2, 4 and 7 after admission were significantly higher in 19 episodes of severe attacks than in 38 episodes of mild attacks (13.71 +/- 9.68, 9.00 +/- 7.54, 6.02 +/- 3.83 vs 4.78 +/- 3.91, 3.30 +/- 3.61, 1.43 +/- 2.08 mg/dL; P less than 0.0001, P less than 0.005, P less than 0.0001, respectively). The sensitivity, specificity and accuracy of predicting a severe attack were 94, 76 and 82% using C-reactive protein greater than or equal to 8 mg/dL on day 2; 67, 92 and 84% using C-reactive protein greater than or equal to 5 mg/dL on day 7; and 59, 76 and 70% using Ranson's criteria greater than or equal to 3. Increases in LDH-4 and LDH-5 isoenzymes were found in both groups, with LDH-4 being slightly higher in severe attacks than in mild attacks. There was no significant difference of erythrocyte sedimentation rate between both groups. When compared with Ranson's criteria, lactate dehydrogenase isoenzymes and erythrocyte sedimentation rate, C-reactive protein is more valuable in the early assessment of the severity of acute pancreatitis.