The amylase concentration of ascitic fluid and serum were measured in patients with various types of ascites to determine their normal range. The mean (+/- SD) nonpancreatic ascites amylase concentration was 42 +/- 44 IU/L (range 4-234) and the mean ascitic fluid/serum amylase concentration ratio was 0.44 +/- 0.33 (range 0.10-1.55). Of the various types of non-pancreatic ascites (sterile cirrhotic, infected, malignant, etc.), no group had a significantly different ascitic fluid amylase concentration or concentration ratio than any other group. Two patients with pancreatic ascites had a mean ascitic fluid amylase concentration of 1,957 +/- 1,093 IU/L and a mean amylase concentration ratio of 5.59 +/- 0.02--both significantly (p less than 0.001) greater than those of nonpancreatic ascites.