Osteoporosis resulting in bone fractures is a complication in patients with primary biliary cirrhosis (PBC). Once-weekly alendronate improves bone mass and is well tolerated in these patients, but there is a concern because of poor compliance. Therefore, the efficacy, adherence, and safety of monthly ibandronate (150 mg) with weekly alendronate (70 mg) were compared in a randomized, 2-year study in 42 postmenopausal women with PBC and osteoporosis. Bone mineral density (BMD) of the lumbar spine and proximal femur (by DXA), liver function, and bone markers were measured at entry and every 6 months over 2 years. Adherence to therapy was assessed by the Morisky-Green score. At enrollment, the two groups were similar with respect to age, BMD, severity of cholestasis, previous fractures, and bone markers. Thirty-three patients, 14 in the ibandronate group and 19 in the alendronate group, completed the trial. At 2 years both treatments resulted in a significant increase in BMD at the lumbar spine (from 0.875 ± 0.025 to 0.913 ± 0.026 g/cm2, P < 0.001 with alendronate, and from 0.898 ± 0.024 to 0.949 ± 0.027 g/cm2, P < 0.001 with ibandronate). The mean percentage change was 4.5% and 5.7%, respectively (P = not significant). BMD increased at the total hip by 2.0% and 1.2%, respectively. Changes in bone markers were similar in both groups and one patient with alendronate developed a new vertebral fracture. Adherence to therapy was higher with ibandronate (P = 0.009). Neither treatment impaired liver function or cholestasis. Conclusion: Both regimens, weekly alendronate and monthly ibandronate, improve bone mass and are comparable in safety for osteoporosis therapy in patients with PBC, although adherence is higher with the monthly regimen. Further larger studies are needed to assess fracture prevention. (Hepatology 2013; 58:2070–2078)