BACKGROUND We wanted to ascertain whether alcohol abuse is associated with a changed faecal bile acid excretion. METHODS Faecal bile acid excretion was studied in seven chronic alcoholic subjects when admitted to hospital for detoxification. Bile acids in faeces and serum were quantified by gas-liquid chromatography and identified by mass spectrometry. RESULTS Daily faecal bile acid excretion was on average 948 mumol in the patients at admission, compared with 400 mumol in eight healthy controls (P < 0.01). The daily faecal bile acid excretion decreased slowly during the detoxification period but was still higher in the patients than in controls after 9 days of detoxification (P < 0.05). Faecal bile acid excretion varied greatly between the different patients, with poor correlation to diarrhoea. In one patient the faecal bile acid excretion was remarkably high, amounting to an average of 6800 mumol day-1 during the first 3 days. The percentage metabolites of total faecal bile acids in the patients did not differ significantly from that of controls. The faecal wet weight was higher in the patients than in the controls, although significantly so only after the first 3 days of detoxification. CONCLUSIONS Faecal bile acid excretion is increased after alcohol abuse. A gradual decrease in faecal bile acid excretion was observed during the 9-day observation period when the subjects abstained from alcohol.