Patients who are diagnosed with osteoporosis and beginning treatment often discontinue their osteoporosis medication relatively early after the start of treatment because of their poor recognition of fracture risk and the asymptomatic nature of osteoporosis. In this study we aimed to assess adherence to treatment with 1 microg alfacalcidol (D), 60 mg raloxifene (R) or a combination of both (D + R) for 1 year in postmenopausal Japanese women with osteoporosis or osteopenia. We defined persistence of D and R as continuing to take tablets for more than 7 of any 14 days immediately before the 1-year visit. A total of 137 subjects aged 49-81 years [64.9 +/- 7.0 years, 16.0 +/- 12.7 years since menopause (YSM)] were randomly assigned to each treatment group. The proportions persisting with each treatment group at 1 year were 61.4, 65.3, 55.1% for D, R and D + R groups, respectively whereas the compliance to each therapy as judged by the medical possession ratio (MPR) at 1 year were 77.5, 93.8, 78.4%, respectively. There were no significant differences in persistence, compliance and the number of subjects who discontinued treatment due to adverse events among each group. We found significant inverse correlations in percent changes at 1 year between compliance and serum BAP in R and D + R groups or urinary (u-) CTX in the R group. The changes in the level of serum BAP and u-CTX were significantly higher in high-compliance patients (MPR > 80%) treated with raloxifene alone or concomitantly with alfacalcidol compared to those in low-compliance patients.