Mice develop acute hemorrhagic pancreatic necrosis with fat necrosis after 4 days of feeding on a choline deficient-ethionine supplemented (CDE) diet. The diameter, weight and histopathology of the gallbladder were determined in mice fed laboratory chow (LC), a choline-supplemented (CS) diet, a choline-deficient (CD) diet, or the CDE diet for 1, 2 or 3 days. A progressive distension of the gallbladder due to accumulation of bile, was observed in mice fed the CS, CD and CDE diets. An analysis of the bile acid composition of the pancreas, serum and gallbladder bile of mice fed the same diets for 3 days was performed. No differences between control and experimental animals were seen in the concentration and distribution of bile acids in the pancreas. It is concluded that: 1) alterations in bile acid constituents are produced by the diets; and, 2) regurgitation of bile into the pancreas of mice fed the CDE diet does not occur. Thus, bile acids do not seem to initiate or participate in the extensive cellular damage that precedes and accompanies the onset of acute hemorrhagic pancreatic necrosis with fat necrosis in mice fed the CDE diet.