The optimal therapy for the prevention and treatment of osteoporosis in primary biliary cirrhosis (PBC) is unknown. Hormone replacement therapy (HRT) prevents osteoporosis, but may promote cholestasis. We performed a double-blind, randomized, placebo-controlled trial of transdermal estrogen/progestin in postmenopausal women with PBC. The 24-month study enrolled 31 patients, but trial uptake was limited and treatment arm dropout was significant. Placebo-treated patients had a higher percentage loss in femoral neck bone mineral density than actively treated patients (-3.76 +/- 1.37% versus 0.21 +/- 1.01%, respectively, P = .058). New fractures occurred in 2 patients on placebo, and in no patients on treatment. The mean monthly increase in bilirubin was not significantly different between groups, but individual data suggest HRT may worsen cholestasis. In conclusion, women with PBC have strong feelings about HRT, and recruitment for this intervention is difficult. Transdermal estrogen/progestin likely provides protection against bone loss in PBC patients, but may worsen cholestasis.