Thalidomide has been reported to be effective in treating graft-versus-host disease, a condition with many clinical and pathological similarities to primary biliary cirrhosis. We performed a double-blind, placebo-controlled pilot study to assess the efficacy of thalidomide in 18 patients with biopsy-proven primary biliary cirrhosis (10 thalidomide, 8 placebo). Each patient was treated for 6 months and had a liver biopsy before and after treatment. Side effects, particularly sedation and fatigue, were more common on thalidomide and two patients were withdrawn from this group. There were no improvements in liver function tests or in liver histology, assessed morphometrically. A number of patients treated with thalidomide reported an improvement in pruritus. This study suggests that thalidomide is unlikely to be effective in altering the natural history of primary biliary cirrhosis. (C) Journal of Hepatology.