Several studies pointed out an altered stool pattern as the most common side effect of auranofin therapy. The major mechanism in the aetiology of auranofin-induced impairment in bowel habit seems to be the inhibition of Na+/K+ ATPase in the gut. In vitro experiments proved that auranofin can affect active bile acid (BA) reabsorption in rat terminal ileum; this action, due to the ability of the drug to reduce Na+ pump activity by inhibiting Na+/K+ ATPase, may make a significant contribution to the auranofin-induced diarrhoea. The ability of auranofin to reduce the Na+ gradient necessary for active BA reabsorption, however, could cause a decrease of serum BA levels in patients taking auranofin before or without the development of an overt diarrhoea. We measured fasting and postprandial serum conjugated BA levels in 10 female rheumatoid arthritis patients before and after one month and two months' auranofin treatment. No patient developed diarrhoea during the chrysotherapy. When oral gold salt therapy was started, we observed a slight decrease in serum BA levels, but difference was not statistically significant. We can conclude that auranofin therapy does not cause BA malabsorption in patients who do not develop diarrhoea during the treatment.