Bone loss is a well-recognized complication of primary biliary cirrhosis (PBC). Although it has been suggested that alendronate might improve bone mineral density (BMD) in PBC, no randomized placebo-controlled trial has been conducted. The primary aim of this study was to compare the effects of alendronate versus placebo on BMD and biochemical measurements of bone turnover in patients with PBC-associated bone loss. We conducted a double-blinded, randomized, placebo-controlled trial. Patients with a PBC and BMD t score of less than -1.5 were randomized to receive 70 mg per week of alendronate or placebo over 1 year. BMD of the lumbar spine and proximal femur were measured at entry and at 1 year. Changes from baseline in BMD and biochemical measurements of bone turnover were assessed. Thirty-four patients were enrolled. Seventeen patients were randomized to each arm. After 1 year, a significantly larger improvement (P = .005) in spine BMD was observed in the alendronate group (0.09 +/- 0.03 g/cm2 SD from baseline) compared with the placebo group (-0.003 +/- 0.02 g/cm2 SD from baseline). A larger improvement (P = .046) was also observed in the femoral BMD of alendronate patients versus placebo. BMD changes were independent of concomitant estrogen therapy. The rate of adverse effects was similar in both groups. In conclusion, in patients with PBC-related bone loss, alendronate significantly improves BMD compared with placebo. Although in this study oral alendronate appears to be well tolerated in patients with PBC, larger studies are needed to formally evaluate safety.