Hepatic bile flow and its bile acid composition were determined in a group of 23 rats receiving 20% (W/v) ethanol by daily intubations 5 times a week over a 10-12 week period and in a control group of 23 rats. The aim was to elucidate the well known role of alcohol in pancreatitis. Chronic ethanol administration resulted in a significant increase in 2-h bile production and bile secretion rates. Molar concentrations of total and individual bile acids were determined by the hydroxysteroid dehydrogenase method after thin layer separation. No significant differences in molar concentrations of total or separate bile acid were observed. Special attention was paid to free bile acids. A spot with a Rf value corresponding to cholic acid was found in 10 rats in each group. This was examined by mass spectrometry using direct inlet technique, but no free cholic acid could be identified. Thus it seems that the changes in the amounts of bile acids are not decisive for the origin of acute alcoholic pancreatitis but that increased bile flow caused by chronic alcohol ingestion may favour reflux of bile into the pancreas, resulting in pancreatitis.